Influence of solid particle size and concentration on centrifugal slurry pump performance

The particle mass concentration and -mass flow rate are fundamental parameters for describing two-phase flows and are products of particle number, -size, -velocity, and -density. When investigating particle-induced heating augmentation, a detailed knowledge of these parameters is essential. In most of previous experimental studies considering particle-induced heating augmentation, only average particle mass flow rates are given, without any relation to measured particle sizes and -velocities within the flow or any indication of measurement uncertainty. In this work, particle number, individual particle sizes, and velocities were measured in a supersonic flow by means of shadowgraphy and particle tracking velocimetry (PTV). The goals are to determine measurement uncertainties, a particle velocity-size relation, and the spatial distribution of number, size, velocity, and mass flow rate across the nozzle exit. Experiments were conducted in a facility with a nozzle exit diameter of 30 mm, at Ma∞ = 2.1 and Re∞ = 8.2e7 1/m. Particles made of Al2O3 and up to 60 µm in size were used for seeding. Particle mass flow rates up to 50 kg/m2 s were achieved. It is shown that an additional correction procedure reduced common software uncertainties regarding shadowgraphy particle size determination from 14% to less than 6%. Discrepancies between calculated particle velocities and experimental data were found. In terms of spatial distribution, larger particles and a higher mass flow rate concentrate in the flow center. The determined particle mass flow rate uncertainty was up to 50% for PTV; for shadowgraphy, it was less than 17%.Graphical abstract

The passivation zone refers to the area where the protective passivation film is formed on the metal surface and is stable. To assess the distribution of high-risk regions of metal erosion-corrosion in passivation zones at normal temperature, a Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model was created to examine metal erosion-corrosion (E-C) behavior in these zones. By changing the mass flow rate, particle size, and particle velocity of inlet particles, the erosion-corrosion loss under multi-attribute coupling was calculated. The results of the multi-attribute coupling of particles show that when the inlet velocity is large, the influence of different particle mass flow rates and sizes on the maximum erosion-corrosion loss is obvious. When the inlet velocity is low, an increase in particle mass flow rate and particle size will lead to a decrease in the erosion-corrosion growth rate and erosion-corrosion loss, respectively, within a certain range. When the particle mass flow rate is larger or the particle size is larger, the erosion-corrosion loss of the elbow is more obviously affected by the change in inlet velocity. Finally, the correlation degrees between the inlet velocity, particle mass flow rate, particle size and the maximum corrosion and wear loss were quantified through the grey correlation degree analysis method.

Particle mass flow rate and particle mass concentration are key parameters for describing two-phase flows, especially for particle-induced heating augmentation analysis. This work addresses the question of how accurate particle mass flow rate can be determined with three non-intrusive measurement approaches, based on shadowgraphy, particle tracking velocimetry (PTV), and scattered light intensity, in supersonic flows. In terms of shadowgraphy and PTV, the particle mass flow rate was determined by measuring individual particle characteristics, namely particle size, velocity, and density, as well as the measurement volume. The presented shadowgraphy procedure is based on the commercial LaVision DaVis software and additional shadowgraphy corrections. Multiple tests were conducted in the experimental test facility GBK of DLR with varying flow conditions, at a Mach number of 2.1, unit Reynolds number (Re∞) ranging from 5e7 1/m to 1.5e8 1/m, total temperature (T0) ranging from 303 to 544 K, and particle materials, namely Al2O3, MgO, and SiO2, in the size range of 1 to 60 µm. Particle size distributions of Al2O3 and MgO particles could be reproduced with shadowgraphy quite well, while the PTV procedure resulted in non-similar distributions. Pycnometer measurements indicated MgO particle density to be significantly lower than reference values. A DaVis parameter variation analysis resulted in a particle mass flow rate uncertainty of shadowgraphy of up to 30%. The particle mass flow rate uncertainty of PTV is approx. 76%, and the respective uncertainty of scaled PTV and scattered light intensity approach is 28%. The particle mass flow rate, measured with shadowgraphy, is 58% higher than those of the semi-axisymmetric scattered light intensity approach, which can be explained by a higher particle concentration at the injection plane.

Dynamic modeling of a particle/supercritical CO2 heat exchanger for transient analysis and control

Aiming at the erosion failure problem of seamless carbon steel 90° elbows in high-temperature and high-pressure steam 
transmission systems of thermal power plants, this study was conducted to accurately reveal the regulatory mechanism of solid 
particle characteristics and gravity effects on erosion rules. Based on COMSOL Multiphysics software, a numerical model of 
steam-solid particle two-phase flow was established, coupling the k-ω turbulence model with the particle tracing method for 
fluid flow. A multi-model comparison strategy, with the E/CRC model as the primary approach and the Finnie, DNV and Oka 
models as supplementary methods, was adopted to carry out systematic simulations. Key factors including particle density, 
particle size, mass, shape factor, inlet velocity, mass flow rate, and gravity in the direction perpendicular to the pipeline were 
focused on to investigate their influence rules on the maximum erosion rate and incident acute angle of elbows. The results 
show that under the working conditions of this study, particle density has a low sensitivity to the erosion rate; particle size, 
mass, shape factor, mass flow rate and inlet velocity all exert a positive effect on the maximum erosion rate; gravity in the 
direction perpendicular to the pipeline will reduce the maximum erosion rate. Meanwhile, particle density, particle size, mass 
and inlet velocity can reduce the incident acute angle to varying degrees; particle shape factor and mass flow rate have no 
significant influence on it; gravity in the direction perpendicular to the pipeline can increase the incident acute angle. This study 
clarifies the core control rules of elbow erosion under the action of multiple influencing factors, which provides key theoretical 
support and engineering technical reference for erosion prediction, protective structure design and service life extension of 
steam pipelines in thermal power plants.

Purpose This study aims to research the erosion wear characteristics and sealing performance of V-regulating ball valve in coal chemical process pipelines, which provides a theoretical reference for improving its antiwear and sealing performance. Design/methodology/approach Taking the V-regulating ball valve as the research object, based on the computational fluid dynamics and the theory of erosion wear, the authors studied its erosion characteristics under different medium parameters and analyzed the sealing performance under the heat-fluid–solid coupling working condition. Findings The erosion wear mechanism of the valve sealing surface is the simultaneous action of cutting and deformation. When the medium flow velocity, particle mass flow rate and particle size increase, the maximum erosion rate and average erosion rate in the V-regulating valve increase. The inner diameter Mises contact stress of the sealing surface is symmetrically distributed in a “wing shape,” and the contact stress of the outer diameter is distributed in a “butterfly shape.” Due to the superposition of thermal stress and pressure stress in the contact transition zone to produce a significant stress concentration. Practical implications The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Social implications V-type regulating ball valve is widely favored by coal chemical enterprises and petrochemical enterprises because of its wide adjustment ratio and good erosion resistance. Originality/value The V-regulating ball valve wear mechanism for cutting and deformation simultaneously, and its wear rate is positively correlated with the medium flow rate, particle mass flow rate and particle size. After the valve is opened, there is a significant stress concentration occurs in the contact transition zone due to the superposition of thermal stress and compressive stress. The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0205/

Purposes: As a conveying method that uses fluid energy to transport materials in pipelines, pneumatic conveying offers advantages including simple structure and flexible pipeline layout. However, long-distance pneumatic conveying in coal mine shotcreting systems faces problems such as poor performance of shotcreting machines, severe equipment wear, which seriously endanger the safety of workers and hinder the construction speed of bolt-shotcrete support. Therefore, determining appropriate operating parameters and developing reliable wear prediction models have become important research objectives. Method: Based on the Eulerian–Lagrangian method and the coupled CFD-DEM approach, the influence laws of three parameters, namely particle size (6–10 mm), particle mass flow rate (3–7 t/h), and fluid flow velocity (10–20 m/s), on the wear of the rotor were investigated. Furthermore, a three-factor, three-level orthogonal experiment was designed, with particle size, particle mass flow rate, and fluid flow velocity selected as experimental factors, to determine the significance ranking of each parameter’s effect on wear. Findings: Experimental results show that when the particle size is 8 mm, the particle mass flow rate is 5t/h, and the fluid flow velocity is 15m/s, the rotor exhibit low wear volume and good conveying stability. It is also found that the particle mass flow rate has the most significant effect on the wear of the rotor, while the effects of fluid flow velocity and particle size are relatively minor. Conclusions: This study overcomes the cumbersome operation issues of traditional process experiments. By combining parameter optimization with CFD-DEM coupled simulation, it provides a new method for selecting the optimal parameter combination.

An automated particle mass-flow control system has been developed for high-temperature falling particle receivers. The system utilizes an electromechanically actuated slide gate that is designed to operate at 750°C to control the particle flow rate falling through the receiver. As the incoming irradiance changes, the particle mass flow rate is automatically adjusted to maintain a desired particle outlet temperature. The system uses the measured particle outlet temperature relative to a desired setpoint temperature and moves the slide gate to increase or decrease the mass flow rate accordingly in a closed-loop feedback control system. The control system components allow rapid movement of the slide gate with sub-millimeter accuracy resulting in a mass flow rate resolution less than 1 kg/m-s. Multiple slide gates can be used in parallel to accommodate large-scale receivers while independently controlling the particle mass flow rate along the width of the particle curtain. Using multiple slide gates (rather than a single larger slide gate) has the additional advantage of accommodating non-uniform irradiances on the particle curtain so that larger particle mass flow rates can be applied to regions of higher irradiance, and vice versa.

In-flight particle diagnostics have enhanced our understanding of thermal spraying and improved coating reproducibility. However, no methodology to verify the measured in-flight particle properties has been proposed in the literature yet. This methodology requires describing the entire free jet from accurate measured values. This study deals with a novel method to verify the measured in-flight particle sizes and velocities by estimating the particle mass flow rate (PMFR) in the free jet. To this end, the entire free jet cross section was divided into several non-overlapping focal planes, and the size and velocity of the in-flight particles were measured by optical diagnostics at these focal planes. The PMFR of the powder feeder was used as a reference to validate the determined PMFR in the free jet. The results showed a good agreement with the PMFR of the powder feeder and could be replicated with different feedstock powders, demonstrating the capability of the developed method. Furthermore, the determined PMFR distribution in the entire free jet, referred to as digital footprint, agreed well with the height of the experimental footprints of the spray jet on a substrate. Consequently, it can be concluded that the spatial PMFR distribution was also properly measured.

In gas and oil industry, erosion damages to pipe lines bends and elbows due to the presence of sand particles have been a challenging issue. In this study a computational model approach was for evaluating the erosion rates in different vertical return bends including sharp bend, standard elbow, 180° pipe bend and long elbow. The airflow in the pipe was simulated using the SIMPLE method and the k-ω SST turbulence model. An Eulerian-Lagrangian approach was used for predicting particle trajectories and the corresponding erosion rates. Different particle sizes and mass flow rates were considered and Oka model for evaluating the erosion rate was used in these simulations. Under the same conditions, the simulation results indicated that the sharp return bends experience the highest erosion rates and the 180° bends experience the lowest erosion among the studied configurations. It was also found that the erosion rate is linearly proportional to the mass flow rate of particles for all cases studied.

Supersonic gas-solid injection technology finds extensive use in drug particle delivery systems. However, the combined impact of particle diameter and mass flow rate on the delivery efficiency remain insufficiently explored. Within the Euler-Lagrange framework, this study utilizes the discrete phase method (DPM) for the numerical simulation of supersonic gas-particle flow in a needle-free injector. After validating the model’s accuracy with experiment results, further investigations were conducted into the influences of particle size and mass flow rate on particle behavior and flow field properties. The results indicate that the impact of larger particles on the compressible structure is stronger, while higher mass flow rate absorbs greater energy from the gas phase, reducing the gas expansion capacity, which results in lower velocity, Mach number, and higher temperature. The jet core zone is approximately x/X = 0.3 in length. Outside core zone, the gas velocity rapidly decays and temperature rises sharply. Within the jet core zone, drug particles are accelerated and cooled, while beyond core zone, they decelerate and heat up. The strongest inter-phase interactions occur primarily in the nozzle expansion area and the jet core zone. Smaller particles reach maximum velocity upstream. This implies that in designing needle-free injectors, the nozzle-to-skin distance must match the drug particle diameter to achieve maximum penetration effectiveness. Furthermore, the particle temperature decreases with smaller sizes. As the particle diameter rises from 10 μm to 100 μm, the minimum temperatures of the particles are 145 K and 264 K, respectively, indicating the need to match the particle diameter with the minimum temperature at which the drug particles remain effective. Additionally, higher mass flow rate doses reduce injection velocity and penetration ability, necessitating the rational control of the administered dose range. These results offer significant theoretical guidance for the design and improvement of needle-free injection.

This paper describes on-sun testing of an automated system that controls the particle mass flow and outlet temperature in a high-temperature falling particle receiver. A slide gate with a linear actuator was designed and implemented in a closed-loop feedback system that varied the particle mass flow rate to maintain a desired bulk particle outlet temperature. The system was designed to operate at high temperatures (>700 °C) and relatively large mass flow rates (∼1 - 10 kg/s and higher). On-sun tests were performed at different irradiances, particle inlet temperatures, and particle mass flow rates. Results showed that the automated system could maintain desired particle outlet temperatures from ∼300 – 650 °C for most test conditions. During significant flux perturbations, oscillations (or ringing) about the desired setpoint temperature was observed, which is common for simple proportional control systems. Future studies will investigate more advanced proportional integral derivative methods to dampen the oscillations and provide tighter controls. Particle temperature rise and thermal efficiency were also measured during the on-sun tests and are reported. Finally, the particle mass flow rate as a function of slide-gate aperture and particle temperature was measured, and a new correlation was derived.

A small-scale single-tube experimental system was established to pretest the workability of a gravity driven moving bed solar receiver. Discharge characteristics of solid particles with various particle sizes range from 149 µm to 1359 µm in mean diameter are studied at ambient temperature. Three models have been set up to predict the mass flow rate in the without-insert case of particle flow experiments. Among them, model-3 is shown to obtain a mean error of 1.54% compared with the experimental results, indicated that the influence of particle size and orifice diameter on the gas-solid slip velocity should be considered. Adding insert in the tubes is proved to increase the mass flow rate of the finest particles compared with that in without-insert case. However, for particles coarser than 642 µm in mean diameter, the effect on is insignificant and the mass flow rate in with-insert case is consistent with predicted results by Beveloo equation and model-3. Besides, the experimental results of particles finer than 297 µm in with-insert case are larger than predicted results by model-3 and less than that by Beveloo equation. It is noteworthy that two kinds of flow instability are observed with specific experimental variables, indicated that particle layer thickness, particle size and orifice diameter are relevant parameters to affect the granular flow state. Hence, optimizing structural parameters and selecting suitable particle sizes are necessary to avoid flow instability in the solar receiver. Besides, a preliminary hot-state experiment showed the stable particle flow at high temperatures, the temperature has negligible effect on the particle mass flow rate.

Velocity characterization of dense phase pneumatically conveyed solid particles in horizontal pipeline through an integrated electrostatic sensor

Gas reservoirs play an increasingly important role in oil and gas consumption and safety in China. To study the problem of erosion and wear caused by gas-carrying particles in the process of gas extraction from gas storage reservoirs, a mathematical model of gas–liquid–solid three-phase erosion of gas storage reservoir columns was established through theories of multiphase flow and particle motion. Based on this model, the effects of the water volume fraction, gas extraction rate, particle mass flow rate, particle size, and bending angle on the erosion location and rate of the pipe columns were investigated. The findings indicate that when the water content volume fraction is low, the water production volume minimally affects the maximum erosion rate of pipe columns. Conversely, the gas extraction rate exerted the most significant influence on the column erosion, showing a power function relationship between the two. When gas extraction volume exceeds 60 × 104 m3/d, the maximum erosion rate surpasses the critical erosion rate of 0.076 mm/a. This coincided with the increased sand mass flow rate, although the maximum erosion rate of the pipe columns remained relatively steady. The salt mass flow rate demonstrated a linear relationship with the erosion rate, with the maximum erosion rate exceeding the critical erosion rate of 0.076 mm/a. The maximum erosion rate of the pipe columns increased, stabilized with larger sand and salt particle sizes, and exhibited an increasing trend with the bending angle. For gas extraction volumes exceeding 46.4 × 104 m3/d and salt mass flow rates exceeding 22 kg/d, the maximum erosion rate of pipe columns exceeds the critical erosion rate of 0.076 mm/a. The conclusions of this study are of some importance for the clarification of the influencing law of pipe column erosion under high temperature and high pressure in gas storage reservoirs and for the formulation of measures for the prevention and control of pipe column erosion in gas storage reservoirs.