Solid Particle Velocity Research Articles

A self-adaptive fractional-order PID controller for the particle velocity regulation in a pneumatic conveying system

This paper presents the methodical development of a state-error-driven self-adaptive fractional-order proportional–integral–derivative (AFOPID) control algorithm to efficiently regulate the velocity of pneumatically conveyed particles at the desired set point and to prevent the blockage of particles in a pipe due to an imbalanced combination of their velocity and corresponding mass flow rate. The proposed fractional control law is constituted by adaptively modulating fractional orders of the integral and differential operators in the control based on the state-error variations in the velocity of solid particles. The particle’s velocity is measured and updated via electrostatic sensors in conjunction with cross-correlation signal processing algorithms. All the other fixed hyper-parameters associated with the proportional–integral–derivative (PID) control scheme are meta-heuristically optimized by using a genetic algorithm. The proposed AFOPID is benchmarked against conventional integer-order PID and the fractional-order proportional–integral–derivative (FOPID) controllers. Experiments are performed on a laboratory-scale test rig to comparatively analyze the aforesaid control schemes, where each controller is examined for three velocity set points and three disturbance levels. The experimental results validate the superior time optimality and robustness of the proposed AFOPID controller against bounded disturbances and abrupt velocity set-point variations by manifesting relatively faster settling time, low overshoots (and undershoots), and smaller steady-state fluctuations.

Settling velocity characteristics of inertial particles in turbulent and wave-induced environments

In the present study, a theoretical model is proposed to calculate the settling velocity of solid particles in turbulence generated by both oscillatory and nearly horizontal flow motions. In contrast to other previous models that typically compartmentalize two flow conditions in their studies, this study takes a more comprehensive approach by considering the combined effects of both conditions. Taking into account the influence of drag nonlinearity, virtual mass and Basset history forces, the new theoretical model is formulated. The proposed model is obtained by solving the particle motion in fluid flow under some reasonable assumptions. Accordingly, we obtain a new dimensionless term to better take into account the effect of turbulence anisotropy on the settling velocity and the role of the sediment damping coefficient. Application of this term for other conditions is discussed in the paper. The present model shows satisfactory agreement with a wide range of experimental and numerical data and with different flow conditions found in the existing literature. These data include homogeneous isotropic turbulence with high resolution direct numerical simulations (DNS), turbulent open channel and vertical oscillation.

Research on multi-velocity measurement method of solid particles based on interdigital electrostatic sensor

Abstract In gas-solid two-phase flow, the velocities of solid particles will show different distributions as the flow pattern changes, and it is a challenging task to achieve the measurement of different velocity parameters in the flow field. To obtain the velocity information of solid particles in the flow field, a novel method to achieve multi-velocity measurement of solid particles is proposed by using the spatial filtering characteristics of interdigital electrostatic sensor with variational mode decomposition (VMD). Firstly, a three-dimensional model of the interdigital electrostatic sensor is established using COMSOL simulation software. Based on its spatial dynamic sensitivity, a theoretical analysis of its spatial filtering characteristics is conducted to obtain a mathematical relationship for velocity measurement. Subsequently, the VMD decomposition method is applied to an experiment involving charged wires, with the experimental results verifying the effectiveness of VMD in achieving multi-scale decomposition of electrostatic signals. Finally, the proposed measurement method is validated on a gravity feeding device and a pneumatic conveying system. The experimental results demonstrate that the method exhibits good feasibility.

The erosion rate prediction for the elbow in shale gas gathering and transportation system: RSM and GA-BP-ANN modeling

Elbow erosion caused by sand mixed in shale gas is a significant issue faced by shale gas gathering and transportation systems, posing a serious threat to the safe and stable production of shale gas. In this paper, the factors affecting elbow erosion in the shale gas gathering and transportation system are identified. The computational fluid dynamics (CFD) two-way coupling Euler-Lagrange method is used to investigate the single-action of various parameters on particle trajectory, erosion morphology, and maximum erosion rate, including pipe inner diameter, pipe R/D ratio, pipe bending angle, pipe bending orientation, solid particle velocity, solid particle size, and solid particle mass flow rate. Subsequently, the response surface methodology (RSM) is employed to quantitatively explore the synergistic interactions between these factors that affect the maximum erosion rate of the elbow, and a surrogate model for simple and rapid evaluation of the maximum erosion rate for elbows at the engineering level is proposed. Finally, the backpropagation artificial neural network (BP-ANN) optimized by genetic algorithm (GA) is used to train the samples obtained by Latin hypercube sampling (LHS) in the multi-factor range. By comparison, the RSM surrogate model and the GA-BP-ANN model reveal a favorable level of agreement with the experimental data, while considering various influential factors. It is important to note that each method possesses distinct advantages, limitations, and specific application environments. This research can provide quantitative references for preventing and controlling erosion within the shale gas gathering and transportation system.

Reduction of pipe wall erosion by creating a vortex flow in anthracite powder pneumatic transport for power plants

From the total electricity generated in South Africa, about 85% is coal based. Coal powder is a solid fuel used in injectors for electricity production. The coal powder is extremely abrasive therefore it is important to maintain a minimum admissible flow speed. As the most severe pipe wall erosion takes place in bends, the most significant factor influencing wall erosion is the solid particle velocity. The aim of this research was to reduce the wall erosion through flow velocity control. Computational fluid dynamics (CFD) simulations, showed that for the same velocity, the erosion is dependent on flow direction change and the ratio between the radius of the bend and pipe diameter. The reduction of flow velocity was achieved by subtracting a spiral volume, from the inner volume of a horizontal pipe, just before an upward or downward bend. The modified volume geometry generated a vortex flow in the bend, achieving a more even distribution of maximum erosion points over the bend surface. The wall erosion, expressed in mm–wall thickness loss/hour, in the modified volume decreased by about 28,8 % while the installation life expectancy increased significantly. Furthermore the bend radius was proved to influence the erosion magnitude and location.

Hydrodynamics of a cold circulating fluidized bed for methanol-to-olefins (MTO) process: experimental and computational investigation

The present study aims to investigate the hydrodynamic behavior of gas–solid flow in a pseudo-two-dimensional cold circulation fluidized bed specifically designed to mimic a plane cut of an industrial methanol-to-olefins (MTO) bed. The solid velocity pattern was experimentally examined using the Particle Image Velocimetry with Digital Image Analysis (PIV-DIA) technique. The hydrodynamics of this pseudo-2D bed were studied using the twoPhaseEulerFoam solver in OpenFOAM, and the adjusted solver was validated through solid particle velocity and solid volume fraction comparisons, showing good agreement with experimental data. Additionally, the study explores different geometries, including symmetric and asymmetric baffles, to understand their impact on the mixing characteristics of the circulating fluidized bed for MTO. The findings highlight the significant role of asymmetric baffles in enhancing mixing behavior. Furthermore, the DIA technique was employed to study the effects of bubbles on gas–solid mixing, revealing that the low mixing region of the bed limited the diameter of bubbles.

Experimental investigation of particle dynamics in particle-laden turbulent boundary layer

In a horizontal wind tunnel, experiments were performed on both particle-free and particle-laden flows at the same incoming velocity. Glass micro-spheres were carried by air along the turbulent boundary layer at a high Reynolds number (Reτ=3200). The Stokes numbers of the solid particles considered were O(10) and O(102). Under a similar volume fraction, Φv=O(10−5), the velocity and spatial distribution of solid inertial particles were investigated using simultaneous particle image/tracking velocimetry measurements and time-resolved particle imaging. This allowed for the exploration of particle dynamics and their corresponding spatial structure in the particle-laden turbulent boundary layer. The results showed that particle–wall (P-W) interaction occurs in both types of particle-laden flows. However, the particle Stokes number directly affects the intensity of the P-W interaction, significantly altering the behavior and spatial organization of particles. The results from the Voronoi tessellation technique confirmed that preferential clustering still happens for the small particle case. In particular, the premultiplied spectra for the particle concentration showed that the temporal pattern of particle clustering presents a similar time-scale to very large-scale motion (around 22δ, where δ is the boundary layer thickness) in the near-wall region.

Numerical simulation of liquid–solid two-phase flow and erosion of Y-type slurry valve with different openings

Most conveyed industrial slurries contain hard particles, and the Y-type slurry valve is eroded after the long-term operation, causing economic losses. In this study, the liquid–solid two-phase flow and erosion characteristics of the Y-type slurry valve were studied. The distribution positions of particles with different sizes were determined, and large particles showed a deposition phenomenon. The particle distributions were more dispersed. At smaller valve opening degrees and the average velocity of solid particles decreased with the increase in valve opening degree. The main erosion area of the valve was concentrated on the ring area around the valve body connecting the downstream pipeline, and the valve disc. The relationship between the particle size and the erosion rate was analyzed, and the distribution of the main erosion area was obtained.

Motion behavior of non-Newtonian fluid-solid interaction foods

The operation object of meal-assisting robots is food with unique rheological properties and complex fluid-solid interactions, which brings great difficulties in the food fetching rate. In this paper, non-Newtonian fluid-solid coupled foods containing thickening gums were investigated by a combination method of experiment and simulation. The viscosity and density of the non-Newtonian fluid were measured by rotational viscometer and densitometer, respectively. The power law model and the Herschel-Bulkley model were used to characterize the shear rheological properties of the fluid foods, respectively. The effects of inclination angle, fetching velocity, and thickening gums on the fetching rate and motion behavior were investigated by a combination method of an explicit algorithm coupling Euler-Lagrange to characterize the fluid-solid interaction relationship. The results show that the non-Newtonian fluid has a higher apparent viscosity at low shear rates for XG: GG = 1:1, however, it has a higher apparent viscosity at high shear rates for XG: GG = 1:2. The consistency index decreases with the temperature increase. It had a larger yield stress for XG: GG = 1:1, which indicated a longer retention of the gel elastic phase when the same shear force was applied. When XG: GG = 1:1, the density of the thickening solution decreases the fastest with the temperature increase. The displacement and velocity of solid particles decrease with the XG proportion increase. This study has reference value for the meal-assisting robot to improve the food fetching rate.

Simulation of sand particles detection inside a pipeline by photon radiography

Transmission pipelines are vital arteries in the petroleum industry, as the survival of this system depends on maintaining the capability of transferring fluid through the pipelines. In petroleum industry, transfer system faults lead to significant economic and social consequences and sometimes may produce critical situations. Transmission pipelines connect all systems, and any defect in their functions adversely affects other systems directly or indirectly.Small quantities of sand particles in transmission pipelines in petroleum industries can cause significant damage to pipes or installations such as valves. Therefore, the detection of these solid particles in oil or gas pipelines is essential. To prevent the costly consequences of passing sand particles through pipelines, early detection of these particles has a crucial impact on equipment lifetime and availability. There are some techniques for the detection of sand particles in the pipelines. Among applicable methods, photon radiography can be applied as an inspection technique along with other methods, or in some cases, where conventional inspection tools cannot be used.The high velocity of solid particles inside the pipeline leads to the destruction of any measuring device that is placed inside it. In addition, the pressure drop due to the placement of the measuring devices inside the pipeline has negative effects on the fluid transfer capacity of the pipe, which ultimately leading adverse economic consequences.In this paper, photon radiography as an in-situ, non-destructive, and online method for detecting sand particles flowing through the pipelines with oil, gas, or brine was studied. Simulation based on the Monte Carlo calculation was applied to evaluate the impact of this technique on sand particle detection in a pipeline. Obtained results showed that radiography, as a reliable, fast, and non-destructive method, could detect solid particles in transmitting pipelines.

ДОСЛІДЖЕННЯ ПОКАЗНИКІВ РОБОТИ ЦИКЛОНА-УТИЛІЗАТОРА З ВИКОРИСТАННЯМ CFD-ПАКЕТА SOLIDWORKS FLOW SIMULATION

It is shown that the use of solid biomass as a renewable energy source is relevant for the production of thermal energy and electrical energy. but the burning of biomass is accompanied by the release of a significant amount of ash into the environment. The need to organize the primary cleaning of waste gases of heat generators in cyclone dust collectors has been established. The stages of solving problems of aerodynamics and heat transfer in the SolidWorks Flow Simulation CFD package are described. The nature of the distribution of pressures, velocities of gas and solid particles in cyclone filters, the values of heat transfer coefficients in the flow area, based on which the studies of cyclone efficiency, hydraulic resistance, power of the heat exchanger-utilizer and the temperature of heated water were performed.It was established that an increase in the temperature of the inlet gas stream reduces the efficiency of the cyclone in cleaning highly dispersed ash, the presence of a heat exchange surface increases the resistance of the cyclone, but improves its efficiency in capturing solid particles up to 10 μm in size. The obtained results make it possible to improve the design, reduce the metal content, and find rational modes of operation of cyclones in operating conditions

Modeling of sand transport and elbow erosion in horizontal two-phase slug flow

Horizontal wells play an important role in maximizing the recovery of hydrocarbons from oil and gas reservoirs. During production, if the rate of production of produced fluids with sand particles is low, the deposition of sand particles in horizontal flow lines can wreak havoc on production systems in such a way as to cause increased pressure loss and reduction or loss of production when the pipe is partially or completely blocked. On the other hand, if the production rate of fluids is high, the impact of sand particles on the wall of the pipe will erode the inner surface of the pipe fittings. In this case, erosion can be severe enough to cause a hazardous spill and complete shutdown of systems. Therefore, it is important to quantify the sand transport and erosivity of different flow regimes. Under moderate velocities, there exists a flow regime which is called slug flow which is characterized by the intermittent appearance of liquid slugs propagating through the pipe. Studying the sand deposition and erosion due to sand particles entrained in intermittent flows is extremely difficult since the solid particle velocity magnitudes are coupled with several multiphase flow parameters such as phase distribution and slippage between the phases. This work focuses on the improvement of mechanistic models for predicting critical deposition of sand particles in horizontal pipes and erosion in horizontal-horizontal elbows. In this investigation, a modified model is proposed to better predict the critical deposition velocity and the characteristic particle velocity as a function of the slug flow characteristics. The model predictions are compared with the sand transport and erosion data collected at the University of Tulsa and other research institutions. The results show that the new approach provides improved predictions for sand transport and maximum erosion in standard elbows when compared with existing models.

Numerical simulation of centrifugal pump impeller erosion caused by particles in lead–bismuth alloy

In order to study the influence of solid particles in lead–bismuth alloy on the safety of nuclear main pump, DPM (Discrete Phase Model) is used to calculate the wear rate of the impeller of nuclear main pump under different operating conditions. By comparing the erosion rate and the most severe erosion area under different working conditions, the most unfavorable operating conditions are obtained. The results show that the erosion of impeller caused by solid particles is the most serious when the inlet velocity of particles u is 0.4[Formula: see text]m/s and particle size D is 100[Formula: see text][Formula: see text]m. Under the small particle size, the impeller erosion concentrated on the suction side of the blade, and under the large particle diameter, the erosion concentrated on the pressure side, and the erosion is more serious. With the increase of solid particle velocity, the erosion of the impeller increases first and then decreases. The erosion severity of impeller and front and rear cover plates caused by solid particles is not consistent. The above research can provide guidance for the anti-wear design and safe operation of the nuclear main pump impeller.

Evaluation of Solid Particle Erosion of EB-PVD TBCs under Thermal Cycling Conditions Based on a Stochastic Approach

The solid particle erosion behavior of electron-beam physical vapor deposition (EB-PVD) thermal barrier coatings (TBCs) was numerically evaluated under thermal cycling conditions. The erosion rates were calculated based on the mechanics-based formulae where the model parameters are fitted to the temperature-process-dependent test data available in the literature. A stochastic approach was applied to simulate the erosion behavior toward service conditions. The mechanics-based formulae were then validated by experimentally measured temperature and sintering-dependent erosion rates from the literature. The pseudoductile erosion behavior is identified for silica particles in the EB-PVD topcoat (TC) erosion system above the intermediate temperatures (~220 °C) due to the softening of partial molten silica particles, thus leading to an increase in the cutting wear and a decrease in deformation wear. The erosion rates are found to decrease versus temperature but increase versus thermal cycles. Such erosion behavior could be attributed to propagation of sintering cracks induced at elevated temperatures. The parametric calculations show that both erosion and thermal cycling parameters have a profound effect on the erosion mechanism of EB-PVD TC. The erosion rate increases at higher solid particle velocity and accumulated mass but displays a pseudoductile erosion behavior versus variation of impacting angles. Two types of erosion mechanisms were evaluated under different thermal cycling conditions. Under the burner cycling test with a short high-temperature dwell period, the erosion mechanism of EB-PVD TBCs is governed by temperature, while under an isothermal cycling test with a high-temperature long dwell period, the erosion is determined by sintering time. The failure mechanisms of EB-PVD TBCs under solid particle erosion processes are discussed combining internal cracking within topcoat and external erosion on the surface of topcoat.

Assessment of the Dimensionless Groups-Based Scale-Up of Gas–Solid Fluidized Beds

The most common scale-up approach for gas–solids fluidized beds is based on matching the governing dimensionless parameters. In the literature, this approach has been validated only by means of measuring global parameters between different sizes of fluidized beds. However, such global measurements are not sufficient to depict all the interplaying hydrodynamic phenomena and hence verify the scale-up relationships. Therefore, to assess this approach, an advanced gas–solids optical probe and pressure transducer measurement techniques have been applied to quantify local hydrodynamic parameters in two different sized fluidized beds. Four different sets of experimental conditions were designed and conducted to examine the assessment of the scaling approach with matched and mismatched dimensionless groups between the two beds. The results indicated that the reported dimensionless groups are not adequate for achieving similarity between the two gas–solids fluidized beds in terms of solids holdup, gas holdup, particle velocity, mass flux, and pressure fluctuation. This finding demonstrates the importance of local measurements of the hydrodynamic parameters of fluidized beds in order to evaluate scale-up relationships. Finally, the results further advance the understanding of the gas–solids fluidized beds and present deeper insight into their solids dynamics.

АЭРОГАЗОДИНАМИКА И ПЕРЕНОС ПЫЛИ ТЕХНОГЕННЫХ МИНЕРАЛЬНЫХ ОБРАЗОВАНИЙ

Of particular interest is the fact that when modeling the convective-turbulent diffusion of dust and gas pollutants, one can use a one-dimensional parabolic type equation, where the convective term will be determined by the wind speed in the surface layer, since the velocity field in the surface layer quickly levels out. The areas of dusty surfaces of a conical AMF do not exceed 60% of its total surface area. When flowing around a spinal-shaped AMT, the air velocity fields can exceed the value of the blow-off velocity of solid particles by almost 30 % of the AMF surface area. At the next stage of research, it is necessary to analyze the simulation results and, on its basis, substantiate technical solutions to ensure the environmental safety of the environment. This will improve the efficiency of technologies to reduce or eliminate the negative impact of AMF on adjacent territories.

Particle flow characteristics in the pipeline of a nonmetallic ore powder air classifier using a DPD-DEM coupled method

Understanding particle flow characteristics can help improve the efficiency of nonmetallic ore powder air classifiers. In this paper, dissipative particle dynamics (DPD) and the discrete element method (DEM) were adopted to study the interactions between the gas phase and solid particles. Gas and solid phases were coupled using the single-particle DPD model. Taking sepiolite particles as an example, at the optimal input air velocity in the pipeline, the gas particle velocity distribution, solid particle velocity distribution, solid particle concentration distribution, and solid particle position distribution were analyzed by numerical simulations. A comparison of numerical simulation and experimental results showed that when the input air velocity in the pipeline was 17 m/s, the velocity of particles and gas in the pipeline gradually increased from the wall to the center of the pipeline. The velocity near the pipeline wall changed rapidly, and the velocity in the main flow area remained basically unchanged. Particles left the pipeline in a uniform and dispersed state and were carried into the classification area. As the input air velocity increased, the pressure drop across the pipeline also increased. Therefore, the optimal input air velocity value could be reasonably selected to minimize energy consumption.

A new two-layer two-phase depth-integrated SPH model implementing dewatering: Application to debris flows

Debris flows can be considered a type of landslide with large velocities and long run-out distances. There are many types of debris flows, depending on the properties of the solid and fluid components of the mixture. The triggering and propagation of debris flows can be studied using a single 3D mathematical model. The computational cost can be very high because of their length, and depth-integrated models provide a good combination of accuracy and cost. Both types of models can be combined in the analysis, using 3D models for initiation and at singular points where more accuracy is wanted. As in a chain where the strength is never higher than that of the weaker link, we have to ensure that all the models are accurate enough in a joint model. This paper deals with a new depth-integrated model which can take into account the changes caused by dewatering in a debris flow. An important limitation of existing two-phase models allowing different velocities of solid and water particles is that when water abandons the mixture, porosity decreases and tends to zero. Here, a two-layer model is introduced, including an unsaturated upper layer on top of a saturated layer.

Numerical Calculation of Solid-Liquid Two-Phase Flow in Open-Design Vortex Pump

This paper mainly based on the CFD platform, numerical simulation of the internal flow field in the open-design vortex pump under different solid particle concentration and particle size is carried out to explore the flow trajectory characteristics of solid particles in the impeller channel and the lateral cavity, as well as the distribution characteristics of solid particles, and calculate the sliding velocity of particles in the impeller channel. The results show that at different solid particle concentrations, the solid volume fraction f in the front and rear cover plate area of the blade is high and that in the middle area is low; The solid volume fraction f decreases gradually from the working face to the back, and the solid particles are widely distributed in the inlet area. Due to the asymmetry of the volute structure, the particle concentration in the inlet area corresponding to the casing tongue is significantly higher than that in other areas; Due to the existence of circulating flow and through flow, the solid particles are distributed in a circular direction in the lateral cavity, and the particle concentration in the middle region is large; In the impeller area corresponding to the casing tongue, the sliding velocity of solid particles decreases with the increase of particle size, and the sliding velocity values of 0.5mm and 1.0mm particle sizes are close.

Investigation on gas-solids hydrodynamics and matching enhancement in feedstock injection zone of double-level nozzle riser

With the development of current energy economy, it is necessary to improve the product distribution of fluid catalytic cracking process, which is achieved by a riser reactor with double-level of nozzles. The new riser is constructed by adding a level of secondary nozzle 0.5 m below the main nozzle of traditional riser. This paper investigates the gas-solids flow and oil-catalyst matching feature based on the optical fiber and tracer technologies. According to the distribution of solids holdup, particle velocity and dimensionless jet concentration, the feedstock injection zone can be divided into the upstream flow control region, the main flow control region, and the secondary flow control region in the radial direction. The size of the regions is changed by the jet gas velocity and axial height. There is a poor match of secondary nozzle jet to particles below the main nozzle. The jet gas from secondary nozzles can improve the matching effect of oil-catalyst near the wall and reduce the probability of coking above the main nozzle.