Search

Mechanical impact superfine grinder is characterized by the wide working condition, high efficiency, and simple operation. The vertical mechanical impact superfine grinder has been commonly used to crush agricultural by-products in recent years. However, the processed material often contains coarse particles with a wide distribution range, due to the current classification chamber structure. The classification performance can also depend mainly on some changes in the vertical position relationship between the current-guide cover and the classification wheel. In this study, two optimization schemes were proposed for the classification chamber using the initial structure, in order to examine the influence of different position relationships on classification performance. Optimized structure 1 involved the current guide that attached to the upper cover, thereby blocking the flow path between them, while maintaining the height of the classification wheel blades. Optimized structure 2 retained the original position of the current-guide cover in consistence with the initial structure, but increased the height of classification wheel blades. Additionally, 3mm was adjusted for the distance between the top edge of the classification wheel blades and the bottom of the discharge port. Firstly, the performance tests were conducted on three classification chamber structures. Secondly, the CFD software and numerical simulation of gas-solid two-phase flow were employed to analyze the flow of fluid within the classification chamber. Finally, the simulation was used to explain the test findings. The following conclusions were also drawn. Optimized structure 1 yielded a more uniform clipping velocity outside of the classification wheel. However, there was a small variation gradient of axial velocity and flow field velocity in the classification chamber. Consequently, the product with the smaller median particle size was obtained in the optimized structure 1, compared with the others. Classification efficiency and accuracy were only changed slightly. The optimized structure 1 resulted in the absence of large particles in the products, due to the blocked flow path in the attachment of the current-guide cover to the upper cover. Meanwhile, the radial velocity decreased gradually from the outer to the inner of the grading wheel in the optimized structure 2. The reverse vortices were generated between the grading wheel blades, leading to a more uniform axial velocity distribution within the grading wheel and a significant variation gradient of axial velocity and flow field velocity within the classification chamber. Consequently, the product with a larger median particle size was yielded, compared with the others, whereas, the classification efficiency and accuracy were enhanced significantly. Moreover, the increasing height of the grading wheel blades impeded the entry of large particles into the finished material. The reason was that the higher tangential velocity outside the grading wheel promoted the material dispersion and the ejection of large particles. In summary, both optimized structures 1 and 2 resulted in the products devoid of large particles. A comparative analysis was performed on the three classification performance indexes, namely product particle size, classification efficiency, and classification accuracy index. Therefore, the optimized structure 2 demonstrated better classification accuracy and efficiency than before, although was yielded a coarser product particle size. Conversely, the optimized structure 1 enabled the production of ultrafine powder with a smaller particle size, although at the cost of lower classification efficiency. The findings can provide a strong reference and theoretical foundation for the flow field investigation and structural optimization of the classification chamber in the CWFJ vertical mechanical superfine grinder. [ABSTRACT FROM AUTHOR]

The phenomenon of pipeline erosion dominated by sulfur particles has become a key research target for sulfur-containing gas-gathering pipelines. Gas-solid two-phase flow of sulfur-containing gases is simulated with a coupled CFD-DPM model in this paper. The Realizable k-ε turbulence model was used to determine the changes in the complex flow field and the Euler-Lagrange method was used to describe the specific trajectory of sulfur particles in the complex flow field. The main erosion trace distribution and the effect of secondary flow effects at the elbow were analyzed and the erosion distribution pattern was investigated for different curvature ratios, particle sizes, and pipe diameters. The results show that the formation of erosion along the tip of the V-shaped erosion trace on the outlet sidewall of the elbow may be related to secondary flow effects. The increase of the curvature ratio RD reduces the erosion intensity of the maximum erosion area, but subsequent increase will result in new secondary erosion trace near the outlet of the elbow and reach the maximum when RD = 8. Variations in particle size will have a significant effect on the extent of the erosion distribution, causing the main erosion distribution of the elbow to vary between 48.2° and 84.2°, while variations in pipeline diameter will have a lesser effect. The Stokes number can also be reduced by controlling the variation in particle size and pipe diameter to alter the force profile on the particles and reduce the erosion effect. [ABSTRACT FROM AUTHOR]

A single–phase flow model was used to analyze the uniformity of the flow field in the desulfurization tower under different baffle combinations, and a multiphase flow model was used to explain the gas and solid two–phase flow characteristics and chemical reaction characteristics in the tower. The stability of the flow behavior of gas and solids in one furnace and two towers was discussed. The results show that the installation of shielding plates at appropriate positions in the tower for sulfur removal is beneficial to enhance the uniform distribution of flow in space, reduce the pulsation interference of bed pressure in the tower, keep the state of gas and solid flow unchanged, and maintain the efficiency of desulfurization at a high level. Reducing the instability of gas–solid two–phase flow is the basis of ensuring the stable switching between single and double towers. [ABSTRACT FROM AUTHOR]

The two-dimensional distribution of gas-solid flow parameters is a great research significance to reflect the actual situation in industry. The commonly used method is the ultrasonic tomography method, in which multiple probes are arranged at various angles, or the measurement device is rotated as that in medicine, but in most industrial situations, it is impossible to install probes at all angles or rotate the measured pipe. The backscattering method, however, uses only one transducer to both transmit and receive signals, and the twodimensional information is obtained by only rotating the transducer. Ultrasound attenuates greatly in the air, and the attenuation changes with frequency. Therefore, COMSOL is used to study the reflection of particles with different radii in the air to ultrasound with various frequencies. It is found that the backscattering equivalent voltage is the largest when the product of ultrasonic frequency and particle radius is about 27.78 Hz ô€€€ m, and the particle concentration of 30% causes the strongest backscattering. The simulated results are in good agreement with the Faran backscattering model, which can provide references for selecting the appropriate frequency and obtaining the concentration when measuring gas-solid two-phase flow with the ultrasonic backscattering method. [ABSTRACT FROM AUTHOR]

Particle settlement and pressure drop in a gas–solid two-phase flow in a pipe with a circular cross-section are studied at mixture inlet velocities (V) ranging from 1 m/s to 30 m/s, particle volume concentrations (αs) ranging from 1% to 20%, particle mass flows (ms) ranging from 5 t/h to 25 t/h, and particle diameters (dp) ranging from 50 μm to 1000 μm. The momentum equations are based on a two-fluid model and are solved numerically. Some results are validated through comparison with the experimental results. The results showed that the gas and particle velocity distributions are asymmetrical around the center of the pipe and that the maximum velocity point moves up. The distance between the radial position of the maximum velocity and the center line for the gas is larger than that for the particles. The particle motion lags behind that of the gas flow. The particle settlement phenomenon is more serious, and the particle distribution on the cross-section is more inhomogeneous as the V, αs, and ms decrease and as dp increases. It can be divided into three areas according to the pressure changes along the flow direction, and the distinction between the three areas is more obvious as the αs increases. The pressure drop per unit length increases as the V, αs and ms increases and as dp decreases, Finally, the expressions of the settlement index and pressure drop per unit length as functions of V, αs, ms, and dp are derived based on the numerical data. [ABSTRACT FROM AUTHOR]

This study was conducted for parameter sensitivity analysis of an eco-friendly fire-fighting device, the sand-ejecting fire extinguisher, by means of experiments and CFD-DEM coupling simulations. The paper presents a total of nine impeller design schemes. Simulations were carried out to reproduce the sand ejection process with each scheme. The results show that the gas flow field has an effect on the ejection process under the windless environment, so the sand ejection characteristic analyses are based on DEM calculations. The phenomenon that a greater number of blades could provide longer ejection distance is also found in the simulation process. Radial and forward schemes may be more suitable for gas-station fires while backward schemes not because of the sand accumulation character. The CFD-DEM calculation shows that increasing the sand mass flow could extend the ejection distance but is more susceptible to ambient wind. [Display omitted] • Gas phase has a little effect on the simulation results in windless environment. • A greater number of blades, a longer ejection distance. • Increasing the sand mass flow could extent the ejection distance. [ABSTRACT FROM AUTHOR]

In this paper, the numerical simulation method of computational fluid dynamics (CFD) is used to establish the flow field model of elbow, including the determination of the applicable gas-solid two-phase flow model and the establishment of the actual basic fluid dynamics equations. After meshing the elbow with ICEM software, the effects of air velocity, bend diameter ratio and other factors on the flow characteristics of the elbow pneumatic conveying are simulated based on FLUENT software. The results show that in the pneumatic conveying with vertical elbows, the flow characteristics of gas-solid two-phase flow have obvious differences with the changes of many factors. [ABSTRACT FROM AUTHOR]

Electrostatic direct velocity tomography method (EDVT) based on electrostatic tomography (EST) is a technology that uses the induced charge signal on the electrode surface through an image reconstruction algorithm to obtain the particle velocity distribution of gas-solid two-phase flow. To simplify the calculation, EDVT assumes that the charge in the imaging region is uniformly distributed. However, due to the complexity of gas–solid flow, this assumption cannot be satisfied, which often brings great measurement errors. To solve the problem, this article proposes an electrostatic charge distribution-based direct velocity tomography (ECDDVT) method by introducing charge distribution information to improve the cross-correlation sensitivity matrix. To evaluate the effect of the particle velocity distribution reconstruction method, this article established an evaluation platform based on a three-dimensional (3-D) simulation of gas–solid flow field and electrostatic field. By assigning the weight value of the number of particles in different pixel units, a more accurate method for measuring the average particle velocity can be obtained. The simulation results and the experiment results of the belt type electrostatic velocity measurement facility show that the performance of the proposed ECDDVT in terms of image correlation coefficient and absolute percentage error (APE) is better than EDVT. The experimental results of the gas–solid two-phase flow rig show that the ECDDVT method can better reflect the particle velocity in the center of the pipe. [ABSTRACT FROM AUTHOR]

Gas–solid two-phase flow and water vaporization processes tend to have a significant impact on the efficiency of flue gas desulfurization with a powder-particle spouted bed. According to the numerical results obtained in this study, the 2D spouted bed developed a classic three-area flow, and the 3D spouted bed entered into a bubbling-like state. The gas and particles flowed in the opposite direction at the junction of the cone and cylinder. The water vaporization rate was higher at the junction of the spout area and the annulus area, lower at the center of the spout area, and the lowest in the annulus area of the 3D spouted bed. Furthermore, it was found that a larger gas velocity, a higher liquid temperature, and a lower gas humidity leads to a higher water vaporization process. [Display omitted] • CFD completed the simulation of water vaporization process in a three-dimensional PPSB. • The main area where water vaporization occurs was the junction between the injection area and the annulus area. • In-depth study of the effect of operating parameters on the rate of water vaporization. [ABSTRACT FROM AUTHOR]

Using a vortex flowmeter is affordable, in addition, simple installation, high reliability, and high accuracy are some advantages of the vortex flowmeter. Vortex flowmeter works based on the vortex shedding principle, hence, the presence of particles in gas-solid flows may results in modulation in the turbulence intensity of the carrier phase and manipulate vortex shedding generated by a bluff body. In this study, the performance of the vortex flowmeter in the presence of particles with different sizes, density, solid volume fraction, and solid mass loading was studied with CFD simulation. The results indicated that the volume fraction and particle diameter are two significant parameters that affect vortex frequency. The vortex frequency is proportional to the velocity of gas flow and volume flow rate is calculated by Q= VA where V is average velocity in a pipe section with the area of A. Notwithstanding the neutral effect of microparticles on vortex frequency, moderate particles lessen the vortex frequency approximately by 20%. To coincide with the increase of solid volume fraction, the vortex frequency will descend, and in the high level of solid volume fraction, the vortex pattern goes to reach the instability. Since the size and volume fraction of the particles affects the frequency and consequently velocity, the gas flow rate measured by the vortex flowmeter is influenced by the presence of the particles. The numerical results have been validated with experimental data. The maximum relative error between the numerical simulation and the corresponding experimental data is 0.46% and 6.72 % for single-phase and gas-solid twophase flows, respectively. [ABSTRACT FROM AUTHOR]

Solid-state synthesis based on supersonic gas flow impingement at room-temperature is an alternative approach to traditional mechanochemical preparation. The supersonic airflow is generated by a convergent-diffusion nozzle with a design Mach number of 3.0. The solid material particles from the suction pipe in the coaxial nozzle can get very high kinetic energy in microseconds. Then the particles impact the target or collide with each other to achieve the transfer of kinetic energy to thermal or chemical energy. We utilize the infrared technology to successfully measure the solid particles' temperature while they impact the target after gathered energy from the supersonic air gas. The results show that the average temperature of the silicon particles with an average particle diameter of 150  μ m after impacting the target is about 6 0 ∘ C, and some of the temperature exceed 2 0 0 ∘ C. It dedicates that the kinetic energy of the particles during the collision translate into internal energy indeed. The work of this paper lays a good foundation for further research on the low-temperature solid-phase reaction processes. [ABSTRACT FROM AUTHOR]

• Array capacitive sensor configured with two excitation modes is evaluated. • Simulation method coupling two-phase fluid and electrostatic fields is proposed. • CFD-DEM is used to build gas–solid two-phase field for particle micro distribution. An array capacitive sensor adopting two excitation modes is designed for measuring local particle concentration in gas–solid two-phase flow. Considering the difficulty in obtaining instantaneous flow parameters under dynamic experiments, a 3D dynamic simulation model coupling gas–solid two-phase fluid and electrostatic fields is proposed to quantitatively evaluate the sensor performance. In the coupling model, Computational Fluid Dynamics and Discrete Element Method are applied to establish two-phase fluid field for particle micro-distribution. The method of defining particle shape and position is used to set permittivity distribution in electrostatic field for coupling gas–solid fluid field and electrostatic field of array capacitive sensor. Using the method of reconstructed image and data fitting, the performance of two excitation modes are evaluated under a typical dynamic flow with structure of stratified flow. Experimental result validates the simulation conclusions and proves the effectiveness of the coupling simulation model for evaluating capacitive sensors in gas–solid flow systems. [ABSTRACT FROM AUTHOR]

• Coal mass flow rate changes nonlinearly with valve opening. • CPFD method is able to reveal flow characteristics of regulating valve. • Regulating valve of pulverized coal will cause local non-uniformity. • The length required to achieve a steady flow downstream of the valve is quantified. Regulating valve of pulverized coal flow is an important gas-solid two-phase valve in the pulverized coal gasification process. Flow characteristics of gas-solid two-phase flow are studied by experimental and numerical approach of computational particle fluid dynamic (CPFD), respectively. The regulation performance of the regulating valve and its influence on the system were investigated. The strong nonlinearity of the relationship between the valve opening and coal flow rate was revealed by experiments and three regions were defined based on the change trend of the coal mass flow rate with the valve opening. Based on the CPFD approach, the process of particles flowing through the regulating valve was observed, and flow parameters including pressure distribution, velocity distribution, and particle volume fraction along the flow channel were analyzed. The model reveals that the presence of the valve introduces strong local inhomogeneities in the gas-solid flow that are studied in order to estimate the regions of the pipe that are mostly affected by the regulating valve. Numerical results indicate that the CPFD method is suitable for the study of pneumatic conveying system with complex flow channels on an industrial scale and can provide a reference for structural design of the regulating valve. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Application of semi-dry flue gas purification in a fluidized bed reactor. • Nozzle expansion angle optimized and its effect on flue gas purification explored. • Large fluidized particles can obstruct the flow of flue gas within the spouted bed. • At Ca/S ratio of 2.5, the desulfurization and defluorination efficiency reach optimal. Semi-dry flue gas desulfurization and purification technology is a promising flue gas treatment technique. This study numerically investigated the influence of factors such as nozzle expansion angle, and fluidized particles diameter on the purification of SO 2 and HF in the spouted bed. The study showed that in nozzle expansion angles of 5-25°, the 10° expansion angle is optimal for SO 2 and HF purification efficiency. The fluidized particles' diameter affects purification efficiency. Desulfurization and defluorination efficiency are optimal when the ratio of fluidized particle diameter to slurry droplet diameter is 15. When Ca(OH)2 accounts for 0.005–0.01 of the slurry, desulfurization and defluorination efficiency are most cost-effective. According to the principle of chemical equilibrium, a higher Ca/S ratio facilitates a complete reaction with SO 2 and HF, ensuring effective purification of the flue gas. The optimal Ca/S ratio is 2.5, with a desulfurization efficiency of 93.55% and a defluorination efficiency of 99.79%. [ABSTRACT FROM AUTHOR]

The LBM-Lagrange tracking method with multiple relaxation time (MRT) model has been developed to predict the flow field and particle deposition a circular or elliptical tube in ash-laden gas turbulent flow with Re of 10,229. The model can be used for predict particle deposition effect on thermal resistance or fouling factor of heat exchangers mostly operating in turbulent flow. Particle deposition morphology on the circular and the elliptical tubes were obtained with the lattice Boltzmann method (LBM). The particle deposition mechanism has been investigated. The dominating mechanism of particle deposition on the circular tube is Brownian diffusion for the Stokes number of 0.002, whereas the dominating mechanism of particle deposition is drag inertia for the Stokes number larger than 0.031. When the long axis of the elliptical tube is parallel to the flow, both the collision efficiency and the deposition efficiency for the elliptical tube are fewer than those of the circular tube which means less particle deposition. It also can be concluded that both ratios of the collision efficiency and the deposition efficiency decrease with increasing axial length ratio of the elliptical tube. The elliptical tube is better than the circular tube as heat transfer surface in the aspect of preventing ash particle deposition. [ABSTRACT FROM AUTHOR]

A non-invasive measurement method of visualizing the flow pattern and charge distribution of gas-solids two-phase flow has been studied and verified using gravity-dropping and pneumatic conveyance rigs with pulverized coal as solids. It has been proven that the permittivity distribution acquired from an electrical capacitance tomography (ECT) system can be used to improve the accuracy in establishing charge sensitivity field of an electrostatic tomography (EST) system, and to reduce the uncertainty of charge distribution reconstruction. The experimental results show that, under the given experimental conditions for the gravity-dropping system, charge density increases with particles' concentration, whilst in the pneumatic conveyance system, charge density decreases in the area where the particles' concentration is higher, and the total charge intensity decreases with the increase of the concentration of pulverized coal in the pipe. The method proposed in this paper is potentially important in pneumatic processes for charge distribution measurement and safe operations. It is envisaged that with further development, this technique can provide information for investigation into the mechanism of inter-particle force on electrostatic attraction and repulsion. [ABSTRACT FROM AUTHOR]

Abstract: Based on the theory of gas–solid two-phase flow and the characteristics of cavern stope a model of dust migration was established. The dust concentration changing of cavern stope by ventilation in 20min after blasting and the dust trajectory in different wind speed were simulated by Fluent Software. The results show that distribution of dust concentration is significantly affected by flow field of airway in cavern, and the dust concentration of inlet is higher than that of outlet and the highest one on the corner of inlet’s side. In the stope, the smaller the wind speed of inlet is, the shorter of dust can be captured, settled and discharged, the more obviously affected by the trajectory of gas flow field. It goes into the stage of clean cycle emissions after 60s, the speed of dust concentration dropped is the biggest between 0s and 70s, the main dust in stope is respirable dust after 70s, it needs much time to settlement. According to the measured data of metal mining, approximately 87% of dust was generated during the drilling and blasting in the mine (). A lot of dust with high concentrations was produced during the cavern stope blasting and it was difficult to be discharged. It can help choose the right speed to rule out the dust quickly which produced during cavern blasting, if the dust concentration distribution and the dust migration law of different inlet velocity in the cavern can be verified, what’s more, the labor productivity can be increased. It has great significance for choosing reasonable ventilation parameters, reducing dust hazards of stope to researching the dust concentration distribution regularity in the stope. [Copyright &y& Elsevier]

Abstract: The objective of this study was to numerically investigate the particle dispersion mechanisms in the gas–solid two-phase jet for a fuel-rich/lean burner by means of coupling the discrete element method (DEM) with the computational fluid dynamics (CFD). The DEM was employed to deal with the particle–particle and the particle–wall interaction in the computation of solid flow; while gas flow was computed by CFD based on the commercial software package Fluent. The particles with various Stokes numbers equal to 0.1, 0.5, 1, 2 and 3 (corresponding to particle diameter 10.8, 24.17, 34.18, 48.38 and 59.21μm, respectively) in the gas–solid fuel-rich/lean jet were investigated in this study. The particle–particle collision was simulated and its effect on the fuel-rich/lean separating performance was evaluated. The results show that the particle–particle collision occurred more frequently with the increasing of Stokes numbers from 0.1 to 3. The particle dispersion became more uniform between the fuel-rich side and the fuel-lean side for particles with small Stokes number; while for particles at St>1, a better fuel-rich/lean separating performance was achieved. The efficiency of the DEM–CFD coupling method was validated by the corresponding experiments, and a good agreement between the simulation and experiments was achieved as a result of the particle–particle collision. [Copyright &y& Elsevier]

This paper describes a strongly coupled calculation procedure for the particle dynamics in electrostatic precipitators (ESPs) subjected to the applied magnetic field with the statistical particle size distribution taken into account. The turbulent gas flow and the particle motion under external forces are modeled by using the commercial computational fluid dynamics code FLUENT. Numerical calculations for the gas flow are carried out by solving the Reynolds-averaged Navier–Stokes equations, and the turbulence is modeled by using the turbulence model. An additional source term, which is obtained by solving a coupled system of the electromagnetic field and charge transport equations, is added to the gas flow equation to capture the effect of the electromagnetic field. The particle phase is simulated by using a discrete phase model. Different kinds of particles which follow the Rosin–Rammler distribution were simulated under different conditions, and the influence of the magnetic field density on the capture of a fine particle was investigated. In order to show the dust removal effect, the collection efficiency and the escaped particle size distribution were discussed in case of different applied magnetic fields. The particle trajectories inside the ESP were also given under the effect of both aerodynamic and electromagnetic forces. Numerical results in the wire-duct ESP show that the collection efficiency increases with the increase of the applied magnetic field, that the particle trajectory is more visible to the direction of the dust collection duct, and that the collection efficiency varies smoothly when the absolute value of the applied magnetic field trends to a certain size. Furthermore, the average diameter of escaping particles decreases and the dispersion for dust particles in different sizes increases with increasing applied magnetic field, and particle sizes are linearly decreasing with the magnetic field before the particle diameter is up to a certain size. [ABSTRACT FROM PUBLISHER]

Abstract: The time-averaged and transient local solid fractions in a gas–solid airlift loop reactor (ALR) were investigated systematically by experiments and CFD simulations. To demonstrate the macro-flow pattern, the time-averaged local solid fractions in four regions of the ALR were measured by optical fiber probe under the conditions of different superficial gas velocities and particle circulation fluxes. The experimental results show that the lateral distribution of time-averaged local solid fraction is a core-annulus or heterogeneous structure in the three regions (draft tube, bottom region, particle diffluence region), but a uniform lateral distribution in the annulus. The operating conditions have different effects on the lateral distribution of time-averaged local solid fraction in each region. In the CFD simulation, a modified Gidaspow drag model considering the formation of particle clusters was incorporated into the Eulerian–Eulerian CFD model with particulate phase kinetic theory to simulate and analyze the transient local solid fraction and the two-phase micro-structures in the gas–solid ALR. The predicted values of solid fraction were compared with the experimental results, validating the drag model. The contours of transient flow field indicate that the flow field of the ALR should be divided into five flow regions, i.e., draft tube, annulus, bottom region, particle diffluence region and constrained back-mixing region, which further improves the understanding of the airlift reactor where only four divisions were determined from the experiments. The transient local solid fraction and its probability density function profoundly reveal the two-phase micro-structures (dilute phase and emulsion phase or cluster phase in the constrained back-mixing region) and explain the heterogeneous phenomenon of solid fraction in the ALR. The dilute phase tends to exist in the center of bed, while the emulsion phase mainly appears in the wall region. The results also indicate that the gas–solid ALR has the common characteristic of aggregative fluidization similar to that in normal fluidized beds. The simulated two-phase transient micro-structures provide the appropriate explanations for the experimental core-annulus macro-structures of time-averaged local solid fraction. [Copyright &y& Elsevier]

• Use the CPFD method to simulate the desulfurization tower. • Obtained the desulfurization characteristics of different regions. • Optimizing the gas-solid flow field can improve the desulfurization efficiency. • Reasonable operating conditions are obtained to improve the desulfurization efficiency. Circulating fluidized bed flue gas desulfurization technology is widely used in the world. The computational particle fluid dynamics (CPFD) numerical simulation method was used to study the gas-solid two-phase flow and desulfurization characteristics in the circulating fluidized bed desulfurization tower. The CPFD method is based on the MP-PIC method, which uses the stochastic particle method for the particle phase and the Euler method for the fluid phase to solve the dense particle flow. The established model was firstly verified by the experimental results of gas-solid flow field and desulfurization efficiency. Then, the effects of flue gas parameters on the flow field in the desulfurization tower and the effects of flue gas parameters, SO 2 inlet concentration, and Ca/S on desulfurization efficiency were numerically simulated. An effective optimization scheme was also proposed to improve the desulfurization efficiency. The research results showed that the CPFD simulation results were in good agreement with the experimental results, which proved the reliability of the method. The particle motion state in the bed of the desulfurization tower presents a core-annular flow. As the flue gas inlet flow increased, the distribution of flue gas and particles has a serious deviation, and the desulfurization efficiency also decreased. The desulfurization efficiency will decrease with the increased of SO 2 inlet concentration and increased with the increased of Ca/S. According to the distribution of SO 2 concentration in the bed, three characteristic desulfurization zones can be proposed, namely, the initial mixing process zone, the high-efficiency desulfurization process zone, and the low-efficiency desulfurization process zone. Installing a baffle at the bottom of the desulfurization tower can optimize the distribution of gas-solid two-phase flow in the bed and the desulfurization efficiency. the computational particle fluid dynamics (CPFD) numerical simulation method is used to study the gas–solid two–phase flow and desulfurization characteristics in a CFB semi–dry desulfurization tower. [Display omitted]. [ABSTRACT FROM AUTHOR]

Discrete mathematical model of dust grain is established based on theory of gas-solid flow. Software Fluent is used to simulate dust movement at 3309 top caving mining face of Chengzhuang coal mine. Different dust distribution rules during cutting coal, removing hydraulic support and caving top coal are obtained from the simulation. Simulation results showed that the dust concentration was different, and so was the location of maximum dust concentration and area of respirable dust. Experiment was performed and the experimental results tally with simulation results. The numerical simulation is reliable and can be used as theoretical guide for developing dust prevention measures. [ABSTRACT FROM AUTHOR]

Swirlmeters are widely used to measure natural gas because of their simple structure, absence of internal moving parts and high measurement accuracy. However, fine particles in natural gas can affect swirlmeters' metering accuracy. Hence, this study evaluated the metrological characteristics of swirlmeters measuring gas–solid two-phase flow with fine particles and different swirler helix angles. Experiments and simulations for swirlmeters with different solid–gas mass ratios and helix angles were performed. The results demonstrated that the swirlmeter meter factors decreased and pressure losses increased as the solid–gas mass ratio increased. With different solid–gas mass ratios, the most effective sensor detection position was at the throat outlet a half radius from the centre of the runner. The swirler with a smaller helix angle could significantly increase the meter factor, while the swirler with a larger helix angle could significantly decrease pressure losses. The swirlmeter internal flow losses were mainly derived from the swirler. • Investigate the metrological characteristics of swirlmeter under different solid-gas mass ratios. • Meter factor of the swirlmeter decreases and pressure loss increases with the increasing of solid-gas mass ratio. • The larger helix angle of the swirler can significantly reduce the pressure loss and flow loss. [ABSTRACT FROM AUTHOR]

Flow behavior of particles is simulated by means of discrete element method (DEM) in a screw conveyor. The gas flow is considered by the Euler model. The subgrid scale model turbulence model is applied to solve gas turbulence. A detailed description of the model equations applied has been presented. The comparison between computational fluid dynamics (CFD)‐DEM (i.e., considering gas flow) and DEM (i.e., not considering gas flow) simulation results is performed. Predicted mass flow rate with CFD‐DEM model is in better agreement with experiments by Roberts and Wills comparing with DEM results. The effects of incline angle and filling rate on the flow behavior of particles are predicted. The simulation results show that the gas flow has a major impact on particle flow behavior at a high rotation speed, whereas the velocity of particles increases with an increase of rotation speed. As the filling rate rises, both the translational granular temperature and the rotational granular particle temperature decline, which means that the particles fluctuation turns weak. While with an increase of incline angle, from the horizontal to vertical, the translational granular temperature is increased, but the rotational granular temperature reduces and then goes up. In brief, translational motion is a main mode of motion in a screw conveyor. [ABSTRACT FROM AUTHOR]