Sand Flow Rate Research Articles

Aerodynamic Behavior of Hump Slab Track in Desert Railways: A Case Study in Shuregaz, Iran

The development of rail transport necessitates expanding environmentally friendly infrastructure. However, specific challenges arise in desert and sandy regions. One innovative solution to manage the effects of windblown sand on desert railways is the use of hump slab track superstructure. This paper develops a solid–fluid aerodynamic model based on ANSYS Fluent 2021 R2 software to simulate the hump slab track during a sandstorm. The model is validated through wind tunnel testing. A case study of a railway sandstorm in the Shuregaz region of Iran is presented, evaluating various sandstorm parameters and hump heights to determine their impact on sand concentration and particle velocity within the sand transit channels. The results indicate that increasing the sand particle diameter (from 150 to 250 µm) leads to higher sand concentration (up to 40%) and lower sand movement velocity (up to 28%). These results have been observed with a higher incremental approach concerning the sand flow rate. Conversely, increasing sandstorm velocity (from 10 to 30 m/s) decreases sand concentration and increases sand movement velocity up to 80% and 150%, respectively. Additionally, a 25 cm hump height significantly enhances sand passage by creating larger channels.

CFD-DEM modelling of particle entrainment in wheel–rail interface: a parametric study on train characteristics

Rail-sanding is employed to improve the train’s wheel–rail traction loss in low adhesion conditions. This can significantly impede trains’ kinematics, operation, and performance by hindering the train’s acceleration and deceleration, resulting in delays and unreliability of transport system as well as causing safety risks and in the worst cases train collisions. Rail-sanding has its own merits in recovering the wheel–rail traction but can result in a sand wastage of more than 80% due to its low sand entrainment efficiency. In this research, computational fluid dynamics is coupled to discrete element modelling to study the behaviour of sand particles during rail-sanding. A parametric study based on the train characteristics, including train velocity, sand flow rate, and the geometry of the sander nozzle, is performed by comparing the entrainment efficiency of the sand particles. It is found that train velocities over 30 m/s result in the entrainment efficiency of almost zero. A moving air layer generated at the wheel–rail interface influences the lower bound of acceptable particle size range. The flow rate and nozzle geometry can be designed to enhance entrainment efficiency.

A Novel Slickwater System with Strong-Polarity Fibers for High-Efficiency Proppant Flowback Mitigation

To avoid or mitigate proppant flowback after a massive hydraulic fracturing of tight formations and to reduce its impairment to well productivity, this study developed a new type of fiber material with strong polarity based on polyester fiber. This fiber material is modified by introducing a strong-polar functional monomer into the molecular structure and adopting the means of surface grafting. On the basis of this fiber material, a fiber slip-water system with excellent dispersion performance can be established to prevent proppant backflow. Laboratory experiments were performed to analyze the specific function of the fibers with strong polarity and its working mechanisms. The results indicate that strong-polarity fibers have excellent dispersion performance. The fibers and resistance-reducing agents form an interwoven structure that can carry proppants, resulting in the enhancement of the sand-carrying capacity of the fracturing fluid system and the overall strength of the sand bank. In terms of the sand-carrying capacity and mitigation of proppant flowback, strong-polar fibers have significantly improved compared to unmodified fibers. In a 5 mm simulated crack, strong-polar fibers can increase the static settling time of 70/140 mesh quartz sand proppant by 26.5%. Meanwhile, the placement height of the sand embankment increased by 23.4% after the settlement of the proppant. In proppant transport experiments, strong-polar fibers with a mass fraction of 0.4% can increase the transport distance of proppants by more than 50%. Within the closed stress range of 2–10 MPa, the concentration of 0.5% strong-polar fibers increases the critical sand flow rate of the proppant by more than twice. The strong-polarity fiber system introduced in this study can be used to develop a fiber slickwater fracturing fluid system suitable for the massive hydraulic fracturing of tight reservoirs and has broad application prospects in the field of proppant flowback mitigation in tight reservoirs.

Study of Water–Sand Inrush through a Vertical Karst Conduit Uncovered through Tunnel Excavation

The existence of karst compromises the safety of underground engineering, especially during tunnel excavations. Karst conduits are uncovered through tunnel excavations, which may lead to a water–sand inrush disaster. Taking a vertical karst conduit as an example, the process of water–sand inrush through a karst conduit could be viewed as being similar to the process whereby a water–sand mixture flows through the discharge opening of a storage bin. In this study, based on force analysis of a non-aqueous sand body above a karst conduit, the limiting diameter of the karst conduit under force equilibrium was obtained. Considering the effect of water on aqueous sand bodies, the criterion of water–sand inrush was established. We aimed to study water–sand migration and inrush through vertical karst conduits in order to obtain the distribution of the water pressure near a vertical karst conduit, and to explore the relationship between the conduit size, water pressure, and water–sand flow rate; therefore, a simulated testing system for analyzing water–sand inrush through a vertical karst conduit was developed. When the water pressure in the testing chamber was close to the critical head pressure of the water–sand inrush, the water–sand inrush exhibited a pattern of instability—migration—deposition—stability. When the water pressure in the testing chamber exceeded the critical head pressure, the water–sand flow increased first and then stabilized over time. With the increase in the set values of the water pressure and conduit size, the steady flow of the water–sand mixture increased gradually. When the karst conduit was opened suddenly, the actual water pressure in the testing chamber decreased significantly, due to the water–sand mixture flowing out of the testing chamber and the water supply lagging behind. With the stabilization of the water–sand flow, the actual water pressure gradually tended towards stability, but it was still lower than the initial set water pressure. When the karst conduit was opened, the values of the water pressure monitored by the pore pressure gauges all clearly decreased. With the stabilization of the water–sand flow, the water pressure gradually became stable. With the increase in the distance between the pore pressure sensor and the karst conduit, the water pressure values all increased gradually. These test results are significant for further studies of the formation mechanisms of water–sand inrush through vertical karst conduits.

The creative solution to improve the locomotive traction and efficiency

The interaction of wheel and rail is the physical basis of train movement on the railroad. It largely determines the safety, speed and level of operating costs. At the same time, the requirements for indicators of interaction between wheels and rails in different contact zones are contradictory. On the one hand, the traction of wheels and rails should be such that low train resistance is ensured. On the other hand - to realize the necessary traction force it is necessary to ensure a high and stable level of traction of locomotive wheels with the rail surface. 
 The work set a goal – to research methods of improving the traction and braking qualities of the locomotive, and to identify the most effective of them. To develop a design which allows increasing traction and braking qualities of a locomotive and providing increasing of ecological safety with application of energy- and resource-saving technologies. As a result an analysis of scientific and technical information sources was carried out which testifies to the existence of different methods of increasing traction and braking qualities of locomotives: structural and operational.
 On the basis of the performed analysis of designs of sand systems used it is established that manual and pneumatic systems were used in the process of locomotives operation, their significant disadvantages and advantages are studied.
 In order to achieve the optimum sand flow rate, preliminary studies on electrostatic and tribostatic sand electrification were carried out, which gave positive results. Both methods are approximately equal in scale of application, the advantages and disadvantages of each of them were studied in detail.
 On the basis of the carried out theoretical and preliminary experimental works a creative solution to improve the design of the resource-saving sand system of the locomotive, modernized on the basis of the tribostatic method of sand charging is developed.
 The developed design allows for the supply of sand directly to the wheel raceway along the rail, which will significantly reduce its consumption, reduce the adverse impact of ground sand on the environment and increase the traction force of the locomotive, by increasing the coefficient of adhesion of the wheel to the rail, which contributes to the improvement of technical and economic indicators locomotive as a whole.

Layering effects of sand samples prepared by travelling pluviators

Travelling pluviators have been commonly adopted to prepare large-scale laboratory sand samples for higher efficiency and consistency. Despite several literature reviews investigating the superiority of such travelling pluviators being able to produce repeatable models, the complex interdependence of the operating variables, in particular travelling speed, on the prepared sand model has not been fully understood to date. In this study, various operating variables of the pluviator – the falling height, deposition intensity (i.e. sand flow rate from orifice) and travelling speed – are studied with three types of sands prepared to desired densities. Through a proposed hypothesis based on energy, the travelling speed was found to have little impact on the sand particles’ kinetic energy for deposition; the influence of the travelling speed on the relative density is realised by altering the layer thickness during pluviation. In addition, it is worth noting that, although the global uniformity can be achieved by preparing sand models in layers in a consistent manner, there exists non-uniformity within each pour in the vertical direction due to particles segregation. This study provides such detail by direct observation of the particle segregation within the layer and the extent of the disturbance by boundary effect of the container.

Study on Erosion Behavior and Separation Efficiency of a Shale Gas Vertical Separator

In a shale gas gathering and transportation station, the sand particles that are not separated by the upstream desander will cause erosion damage to the vertical separator. In response to this problem, based on the field data of a production well in the Changning area, the corresponding mathematical model and vertical separator geometric model were established. On the basis of the software FLUENT, the effects of different gas velocity, particle size, and sand mass flow on the erosion of the separator and the motion of particles were simulated. The corresponding results show that the erosion scar of the inlet baffle presents a ring shape, and the maximum erosion position on the wall changes with the increase of gas velocity. The erosion rate of the inlet baffle is proportional to the sand flow rate and geometrically related to the gas velocity; the maximum erosion rate of the vertical separator is 520 μm/a under the conditions of 6 kg/d sand input; the separation efficiency decreases with the increase of particle size and speed.

Full-loop study of a dual fluidized bed cold flow system: Hydrodynamic simulation and validation

The unsteady behaviors of the air-silica sand flow in a lab-scale dual fluidized bed gasification cold flow system have been studied. A two-dimensional computational fluid dynamics full-loop model with poly-size distribution in solid phases was developed as an innovation of this study to investigate the effects of crucial parameters on system hydrodynamics. The results showed a decrease in the mixture static pressure from the bottom to the upper regions of the system, which maintained the system operations stable. The riser air inlet velocity and the gasifier static bed height were found to play considerable roles in enhancing the total sand flow rates. The same tendencies in the prediction and experiment of both the mixture pressure and the sand flow rate showed the feasibility of the proposed model. Besides, the residual evaluation enhanced data reliability and supported model validation. Especially, undesirable phenomena possibly occurring in the system operation under improper conditions could also be predicted. Accordingly, the inventory of bed material and the fluidizing gas flow rates should be suitably regulated to maintain pressure balances, trouble-free continuous flow, optimal sand circulation rate, and low solids loss. Furthermore, the obtained results in this study can be used as a reference for optimizing the designs and operational conditions of large-scale plants.

Improving sand flow rate measurement using the wavelet transform and ultrasonic sensors

Abstract Accurate sand flow rate measurement is needed to minimize the side effects of sand production in gas fields. There are concerns about the accuracy of sand flow measurement using the sand measuring devices available on the market. In this paper, ultrasonic sensors and discrete wavelet transform signal analysis method is used to measure the sand flow rate. It is found that the strength of the discrete wavelet coefficients in the frequency range of 15–62 kHz has a linear relationship with sand flow rate. This finding provides a new methodology to accurately measure sand flow rate. The proposed method does not need fluid velocity as a prerequisite for sand rate measurement, so it greatly simplifies the system design when flow meters are not used for fluid velocity measurement. Also, this method has a much simpler calibration procedure compared to that of the sand detectors commonly used in the industry.

Modeling of a Railway Sanding System Using Vibration Fluidization

The model of the sand distributor of the sand feeding system of traction rolling stock, the operation of which is based on the effect of vibration fluidization of sand, has been considered. A pneumatic pulsator was used as a source of vibration impact. Experimental studies have shown that this design allows for a continuous regulated supply of sand. The power of the sand distributor membrane vibrations at the disturbing frequency can be used as a criterion characterizing the impact of the pulsator on the sand. There is a close to linear dependence of the sand flow rate on the power of vibrations.

Improving sand flow rate measurement of commercial ASDs and comparison with ultrasonic spectral analysis and filtering

Production of sand in gas wells is associated with various issues such as the erosion of pipes, disruption of the gas processing plant and reduced production capacity. Sand production can jeopardise the integrity of the pipes/equipment. Measuring the sand flow rate helps better sand control and management. Currently, there are many concerns about the accuracy of sand flow rate measurement using a commercial acoustic sand detector (ASD). This study suggests a relationship which substantially improves the accuracy of sand flow rate measurement using an ASD. This study also investigates using a simple ultrasonic sensor for sand flow rate measurement in which a fast Fourier transform (FFT) is used to convert data into the frequency domain. When a Savitzky–Golay filter is used on the FFT response, the smoothed output shows that there is a close relationship between the peak value of smoothed FFT signal in the 10–50 kHz frequency range, and the sand flow rate. This relationship provides a more accurate measurement of sand flow rate than is presently available using an ASD.

Inelastic Behavior of En 31 Steel Metallic Surface Subjected to Hard Body

In machineries of thermal power plants elements such as coal conveying systems, grinding balls, slurry carrying systems involves transfer of load and displacements. In all these machineries every element is subjected to the hard body such as particles from coal and slurry cause continuous wear results with abrasive wear. Due to this abrasive wear there is inelastic and damage of both the objects was takes place. Since many elements of all these machineries were made from En category steels this study was focused on En 31 steel. In the present study rubber wheel abrader was used to conduct the experiments. 106 microns, 212 microns and 425 microns graded abrader was used for conducting the test. En category steel i.e. En 31 was used as target material for the studies. The sand flow rate of 95 grams/minute was maintained. The weight loss was calculated and found that 0.004, 0.012 and 0.021, for an abrader size of 106 microns following with 0.005, 0.012 and 0.020 & 0.007, 0.022 and 0.023 for an abrader size 425 microns. For all these three tests a normal load of 11.37 N, 35.31 N, and 58.85 N was applied. Scanning electron microscope (SEM) was used to study the morphological analysis. There is light influence on volume loss due to the influence of abrader. Weight loss of the material does not solely depend on increasing in abrader size. Inelastic deformation and wear modes are seen as subject to mechanical properties of the target material. Disfigurement highlights describe the volume loss of the wear.

Prediction and research on the erosion of the tubing joint in high yield gas well

Sand production in high-yield gas-well is a common problem in oilfield. Erosion caused by sand production, often leads to pipeline failures and even endangers lives and property if serious. So, the sand production problem cannot be ignored. In this paper, computational fluid dynamics are used. I conduct numerical simulation in allusion to the process of gas flowing through pipeline with sand, with FLUENT software, and then discuss the influence on erosion caused by the flow velocity of gas, the flow rate of sand, the diameter of particles and so on. The following conclusions are drawn: with the increase of natural gas flow rate, the average erosion rate at the tubing joint increases gradually and is approximately exponential to the natural gas flow rate; with the increase of sand flow rate, the average erosion rate at the tubing joint increases gradually and is approximately linear to the sand flow rate; with the increase of sand particle size, the erosion rate at the tubing joint decreases gradually.

Manufacturing of Erosion Measuring Rig for Polymers and Their Composites with some Experimental Results

Solid Particle Erosion System was manufactured as a laboratory and according to the ASTM G76 specifications in a horizontal position with a feeder screw, as the system consists of the main parts: air compressor, voltage regulator, and rubber connection hoses. And the main parts of the rig: nozzle, screw, DC motor, transmission pipes, and Installation platform. The nozzle was made of low alloy steel and hardened by water-quenching, and the conical nozzle cavity was made to insert sand into the nozzle barrel. Tolerance was chosen between the screw and cylinder in practice, with a tolerance of (4 mm) out of two experiments that were tried (2, 4 mm). So, the tolerance was chosen based on the used particles (erodent) in different ranges (150-350 µm), (350-500) µm) and (500-710 µm), preferably a tolerance that gives a smooth spin rotation. One of the things to consider is the stability of the sand flow rate and the issue of overflow or vice versa is the occurrence of a stop flow, and taking into consideration the calibration between the spin rotation and the pressure of the air. Also, the sizes of sand particles used can determine several things, including tolerance, the diameter of the nozzle barrel, and the velocity of particles that can be taken. The rig was tested for specimens of unsaturated polyester (UP) and its composites reinforced with (5 wt. %) of silicon carbide, where the experiment was carried out at an impingement velocity (25.2 m / s) and impingement angles (30°, 60°, 90°) and the size of the erodent from sand Silica has a size of (350-500 µm), so the results showed that the polyester gave the highest erosion rate at the angle (90°), which indicates its brittle behavior, while its composites gave the highest erosion rate at the angle (60°), which indicates its semi-ductile behavior. It is comparing the results obtained with previous research that shows that the rig gave positive results, and it can measure the rate of erosion of polymeric materials and their composites.

Numerical Prediction of Sand Erosion in Elbows

In the present article, turbulent flow of crude oil and sand particles in piping system with a 90° elbow is analysed using computational fluid dynamics simulations. The flow of the crude oil is modelled as continuous fluid which is govern by the continuity and Reynold-averaged Navier–Stokes equations. The Discrete phase model is used for sand particle flow. The governing parameters considered in the present study are: the inlet velocity, spherical sand particle size and sand mass flow rate. The maximum erosion rate is found on the outer surface of the elbow where the sand and fluid impinging the surface before changing the flow direction. It is found that the erosion rate is increasing with the increase of the inlet velocity of the crude oil. The numerical results show that the large sand particles with constant sand flow rate causing less erosion rate than those of smaller diameter. The results show also that the increase of the sand mass flow rate leads to the increase of the erosion rate.

Optimal design for real-time quantitative monitoring of sand in gas flowline using computational intelligence assisted design framework

Abstract Global demand for oil and gas is still increasing rapidly. The direct consequence of this is the increased operating pressure amid concerns over increasing sand production. According to the Society of Petroleum Engineers (SPE), 70% of the world's hydrocarbon reserves are contained in reservoirs situated on unconsolidated formations. Given the reality of these formations, sand production will certainly be a problem of significant concern particularly during the later life of the fields when they become more ‘mature’. However, to monitor sand and optimise its production for improved recovery and safety, life extension and economy of the fields and ensured reliability, the automatic detection and prediction of sand flow characteristic measurements; sand flow rate (SFR), sand concentration (SC), line pressure drop (PD), and gas velocity (GV), has become an important research topic of great interest. Despite this importance, discussion of the topic is still lacking in the literature. This paper proposes a novel and robust architecture of intelligent real-time sand flow characteristic measurement using an acoustic sensor and computational intelligence assisted design (CIAD) framework. It fully incorporates acoustic signal processing and analysis, prediction algorithms and optimisation algorithms in the design. Acoustic features based on acoustic signal processing techniques are extracted to reduce the dimensionality of the acoustic signals. A classical Artificial Neural Network (ANN) is used to model the non-linear relationships between the acoustic signal characteristics and the flow characteristics measurands. In addition, the ANN algorithm adapts its weights and biases using the Grey Wolf Optimiser (GWO) through minimisation of the cost function during the training phase. Preliminary results obtained on a laboratory test rig demonstrate that an acoustic sensor coupled with CIAD may provide simple and robust practical solution to the measurement problem of particle-laden gas flow characteristics in real-time.

Numerical predictions of sand erosion in a choke valve

Two-phase turbulent flow of crude oil and sand in a choke valve is analysed in the present article using 3D computational fluid dynamics simulations. The discrete phase mathematical model is used to simulate the sand flow and its interaction with the oil flow in the system. Parametric study is done to identify the governing parameters to minimize the sand erosion in the system. The valve geometry and dimensions are taken from an industrial oil production project. The parameter considered in the present study are the percentage valve opening, flow rate of the sand and the pressure difference between the inlet and outlet pipes. The simulation results are presented to show the erosion rate variation with the valve opening, sand flow rate and the pressure difference. It is found that the erosion rate is high for small valve opening as well as large valve opening. Minimum erosion rate is found when the valve opening is between 20-30% for all the cases with various pressure differences. Locations of maximum erosion rate are predicted in the simulations.

High-temperature erosion behaviour of plasma-sprayed NiCrBSi–graphite coatings

ABSTRACTPlasma-sprayed NiCrBSi–graphite coatings have been subjected to solid particle erosion at elevated temperatures. The work reports the erosion resistance of NiCrBSi coatings with 4, 6 and 8 wt-% addition of graphite and optimum graphite content for erosion resistance. The coatings were analyzed using optical microscopy, XRD and scanning electron microscopy. Testing was carried out using air-jet erosion test rig, at an impact velocity of 70 m s−1 and at 45° and 90° angles with sand flow rate of 1 g min−1 at RT, 500°C and 650°C. Morphology of eroded surface shows crater, lip, groove formation and chipping as visible mechanism of material removal. Coating with 4wt% distribution of graphite exhibits higher erosion resistance as compared to the coating without graphite addition and improved microhardness. Microstructure images reveal that increase in graphite content above 4% results in the segregation of graphite and leading to soft islands in the coatings thereby decreasing the erosion resistance.

Research on distribution performance of desert sand for heat storage in downcomer

ABSTRACTIn this research, desert sand is used as the sensible heat storage medium, which exchanges heat with air in the downcomer to realize heat storage and heat release. The desert sand distribution uniformity has a significant impact on the heat exchange performance and efficiency between desert sand and air for the process of convection in the downcomer. Given the superiority of sensible heat storage in convective heat transfer between desert sand and air, distributors with cylinder or conical bore solid particles and homogeneity performance testing device are designed and manufactured on the basis of convection system equipped with solid particle–air downcomer. Then, the convection experiment between solid sand and air is researched. The greater the desert sand flow rate and higher the volume density, the larger the variance of regional mass flow rate and the worse the homogeneity performance. For the cylinder bore distributor, the smaller the sand particle size is, the greater affected the sand groups can be. The sand homogeneity performance is preferable with the two particle size ranges: 0.18-0.25 mm and 0.15-0.18 mm. The total sand flow rate decreases, but the uniformity improves with the increase of the air flow velocity, and the best distribution performance is achieved at an air velocity of 0.6 m/s. However, the distribution performance declines with the air flow velocity persistently increasing because the sand groups are pushed to one pipe side close to the wall. The sand groups deflect seriously with the air flow velocity increasing.

Optimisation of a railway sanding system for optimal grain entrainment into the wheel–rail contact

To combat adhesion loss, sand is fired into the wheel–rail contact via a hose using compressed air typically from a storage hopper mounted to the under frame of the train. Many passenger trains in the UK are fitted with stepped braking controllers which range from 1 to 3 with a fourth step being ‘emergency braking’.1 Sand is fired automatically if wheel slip is detected from brake step level 2 upwards.2 Sand is automatically fired when the emergency brakes are applied irrespective of whether low adhesion/wheel slip has been detected.2 For adhesion loss in traction, sand can be applied at the driver’s discretion. Current railway standards2 govern the maximum permissible sand flow rate to protect against wheel/rail isolation of track circuits, but do not address the hose position. This results in a range of hose set-ups across different train types, some of which may not be effective at delivering sand. The work here was carried out using a full-scale laboratory rail–wheel test machine to find the position for the hose and sand flow rates that give optimum sand entrainment to the contact. It was found that ideally the hose should be aimed at the rail or nip and be as close to that contact as safely possible. The use of a 20 mm bore nozzle on the end of a 25 mm bore hose increased sand passing through the contact by up to 70% relative to widely used 25 mm bore hoses without a nozzle. Reduction in sand flow rate below the 2 kg/min threshold significantly reduced the amount of sand entering the contact. It was also shown that relatively small movements in the hose/nozzle from its ideal position and cross winds significantly reduced sand entrainment.