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Particuology 2023年第8期79卷 95-108页

作者： Zhenyu Yang Fei Yan Panpan Tu Rui Zhu School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang212000China School of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang212000China

In the pneumatic conveying process,particles move to the bend under the influence of inertia to form a particle rope,which will cause serious wear between the particles and the pipe wall,and then the dune model is designed and installed in the 90° bend to reduce energy consumption and wear in this study.Firstly,the minimum pressure drop velocity of particles transported by different size dune models was obtained through experimental study.Then the energy saving mechanism of the dune model is studied by CFD-DEM coupling.The experimental results show that the installation of the dune model reduces the minimum pressure drop velocity.The numerical simulation results show that the number of collisions between the particles and the tube wall in the vertical tube decreases after the installation of the dune model,which reduces the energy loss.Moreover,the increasing of tail size of the dune model is beneficial to the diffusion and acceleration of the particles in the vertical tube.

关键词： pneumatic conveying Dune model CFD-DEM Minimum pressure drop velocity Recursiveanalysis

Comprehensive Euler/Lagrange modelling including particle erosion for confined gas-solid flows

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Particuology 2024年第1期84卷 209-235页

作者： Guiherme A.Novelletto Ricardo Martin Sommerfeld Multiphase Flow Systems Institute of Process EngineeringOtto-von-Guericke-University MagdeburgHoher Weg 7b06120Halle(Saale)Germany

The present research aims to assess the capability of a comprehensive Euler/Lagrange approach for predicting gas-solid flows and the associated solid particle erosion.The open-source code OpenFOAM®4.1 was used to carry out the numerical simulations,where the standard Lagrangian libraries were substantially extended to account for all necessary models.Particles are tracked considering both translational and rotational motion as well as all relevant forces,such as gravity/buoyancy,drag and transverse lift due to shear and particle rotation.The tracking time step was dynamically adapted ac-cording to the locally relevant time scales,which drastically reduces computational times.Stochastic approaches are adopted to model particle turbulent dispersion,particle collisions with rough walls and particle-particle interactions.Five solid particle erosion models,available in the literature,were considered to estimate pipe bend erosion.Three study cases are provided to validate the adopted nu-merical approach and erosion models extensively.The first case intends to evaluate the ability of the extended CFD code to predict the behaviour of gas-solid flows in pneumatic conveying systems.This goal is achieved by comparing the numerical results with the experimental data obtained by Huber(1997)and Huber and Sommerfeld(1994,1998)in a pneumatic conveying system.Here,the importance of considering inter-particle collisions and surface roughness for predicting particle velocity,mass flux and mean diameter distributions in gas-solid flows is highlighted.The second and third case intend to evaluate the ability of the erosion models in estimating bend erosion in diluted gas-solid flows.The erosion data obtained experimentally by Mazumder et al.(2008)and Solnordal et al.(2015)in very dilut pneumatic conveying systems is used for validating the numerical results,neglecting now inter-particle collisions and two-way coupling.Besides a comprehensive analysis of the different influential properties on erosion,the innovation of the present stud

关键词： pneumatic conveying Pipe bend Numerical calculation(CFD) Euler/Lagrange approach Erosion models Wall roughness

Numerical study of coarse coal particle breakage in pneumatic conveying

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Particuology 2018年第3期16卷 204-214页

作者： Jiawei Zhou Yu Liu Changlong Du Songyong Liu Jianping Li School of Mechatronic Engineering China University of Mining and Technology Xuzhou 221116 Jiangsu China School of Mechanical and Power Engineering Henan Polytechnic University Jiaozuo 454000 Henan China

pneumatic conveying of coarse coal particles with various pipeline configurations and swirling intensities was investigated using a coupled computational fluid dynamics and discrete element method. A particle cluster agglomerated by the parallel-bond method was modeled to analyze the breakage of coarse coal particles. The numerical parameters, simulation conditions, and simulation results were experimentally validated. On analyzing total energy variation in the agglomerate during the breakage process, the results showed that downward fluctuation of the total particle energy was correlated with particle and wall col- lisions, and particle breakage showed a positive correlation with the energy difference. The correlation between the total energy variation of a particle cluster and particle breakage was also analyzed. Parti- cle integrity presented a fluctuating upward trend with pipe bend radius and increased with swirling number for most bend radii. The degree of particle breakage differed with pipeline bending direction and swirling intensity： in a horizontal bend, the bend radius and swirling intensity dominated the total energy variations： these effects were not observed in a vertical bend. The total energy of the particle cluster exiting a bend was generally positively correlated with the bend radius for all conditions and was independent of bending direction.

关键词： Computational fluid dynamics-discreteelement method pneumatic conveying Pipeline configuration Swirling intensity Coarse coal particle Breakage

Predicting the mode of flow in pneumatic conveying systems—A review

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Particuology 2008年第5期6卷 289-300页

作者： Mark G.Jones Kenneth C.Williams Centre for Bulk Solids and Particulate Technologies School of EngineeringUniversity of NewcastleNewcastle 2308Australia

An initial prediction of the particulate mode of flow in pneumatic conveying systems is beneficial as this knowledge can provide clearer direction to the pneumatic conveying design process. There are three general categories of modes of flow, two dense flows： fluidised dense phase and plug flow, and dilute phase oniy. Detailed in this paper is a review of the commonly used and available techniques for predicting mode of flow. Two types of predictive charts were defined： basic particle parameter based （e.g. particle size and density） and air-particle parameter based （e.g. permeability and de-aeration）. The basic particle techniques were found to have strong and weak areas of predictive ability, on the basis of a comparison with data from materials with known mode of flow capability. It was found that there was only slight improvement in predictive ability when the particle density was replaced by loose-poured bulk density in the basic parameter techniques. The air-particle-parameter-based techniques also showed well-defined regions for mode of flow prediction though the data set used was smaller than that for the basic techniques. Also, it was found to be difficult to utilise de-aeration values from different researchers and subsequently, an air-particle-based technique was developed which does not require any de-aeration parameter in its assessment.

关键词： pneumatic conveying Mode of flow Dense phase Permeability De-aeration

Numerical simulation of fluidized dense-phase pneumatic conveying of powders to develop improved model for solids friction factor

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Particuology 2017年第6期15卷 42-50页

作者： Baldeep Kaur Anu Mittal S.S. Mallick Renhu Pan Soumendu Jana School of Physics and Materials Science Thapar University Patiala Punjab 147004 India Department of Mechanical Engineering Thapar University Patiala Punjab 147004 India Fujian Longking Co. Ltd. Longyan Fujian 364000 China

Accurate prediction of the solids friction factor through horizontal straight pipes is important for the reliable design of a pneumatic conveying system, but it is a challenging assignment to date because of the highly concentrated, turbulent, and complex nature of the gas-solids mixture. Power-station fly ash was transported through different pipeline configurations. Numerical simulation of the dense-phase pneumatic conveying systems for three different solids and two different air flow rates have shown that particle and actual gas velocities and the ratio of the two velocities increases in the flow direction, whereas the reverse trend was found to occur for the solids volumetric concentration. To develop a solids friction-factor model suitable for dense-phase flow, we modified an existing pure dilute-phase model by incorporating sub-models for particle and actual gas velocities and impact and solids friction factor. The solids friction-factor model was validated by using it for scale-up predictions for total pipeline pressure drops in longer and larger pipes and by comparing experimental and predicted pneumatic conveying characteristics for different solids flow rates. The accuracy of the prediction was compared with a recently developed two-layer-based model. We discussed the effect of incorporating the particle and actual gas velocity terms in the solids friction-factor model instead of superficial air velocity.

关键词： pneumatic conveying Dense-phase Numerical analysis Pressure drop Scale-up validation

Energy loss at bends in the pneumatic conveying of fly ash

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Particuology 2015年第4期13卷 65-73页

作者： Naveen Tripathi Atul Sharma S.S.Mallick P.W.Wypych Department of Mechanical Engineering Thapar University Faculty of Engineering and Information Sciences University of Wollongong

An accurate estimation of the total pressure drop of a pipeline is important to the reliable design of a pneumatic conveying system. The present paper presents results from an investigation into the modelling of the pressure drop at a bend in the pneumatic conveying of fly ash. Seven existing bend models were used （in conjunction with solids friction models for horizontal and vertical straight pipes, and initial acceleration losses） to predict the total pipeline pressure drop in conveying fly ash （median particle diameter： 30 }zm; particle density： 2300 kg/m^3; loose-poured bulk density： 700 kg/m3） in three test rigs （pipelines with dimensions of 69 mm inner diameter （I.D.） × 168 m length; 105 mm I.D. × 168 m length; 69 mm I.D. × 554 m length）. A comparison of the pneumatic conveying characteristics （PCC） predicted using the seven bend models and experimental results shows that the predicted total pipeline PCC and trends depend on the choice of bend model. While some models predict trends that agree with the experimental results, other models predicted greater bend pressure drops for the dense phase of fly ash than for the dilute phase. Models of Pan, R. （1992）. Improving scale-up procedures for the design of pneumatic conveying systems. Doctoral dissertation, University of Wollongong, Australia, Pan, R., ＆ Wypych, P.W. （1998）. Dilute and dense phase pneumatic conveying of fly ash. In Proceedings of the sixth International Conference on Bulk Materials Storage and Transportation （pp. 183-189）, Wollongong, NSW, Australia and Chambers, A.J., ＆ Marcus, R.D. （1986）. pneumatic conveying calculations. In Proceedings of the second International Conference on Bulk Materials Storage and Transportation （pp. 49-52）, Wollongong, Australia reliably predicted the bend losses for systems conveying fly ash over a large range of air flows.

关键词： pneumatic conveying Fluidised dense phase Bend Pressure drop Bend model

Characterization of the gas pulse frequency,amplitude and velocity in non-steady dense phase pneumatic conveying of powders

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Particuology 2008年第5期6卷 301-306页

作者： Kenneth C.Williams Mark G.Jones Ahmed A.Cenna Centre for Bulk Solids and Particulate Technologies School of EngineeringUniversity of Newcastle

Current modelling techniques for the prediction of conveying line pressure drop in low velocity dense phase pneumatic conveying are largely based on steady state analyses. Work in this area has been on-going for many years with only marginal improvements in the accuracy of prediction being achieved. Experimental and theoretical investigations undertaken by the authors suggest that the flow mechanisms involved in dense phase conveying are dominated by transient effects rather than those of steady state and are possibly the principal reasons for the limited improvement in accuracy. This paper reports on investigations on the pressure fluctuation behaviour in dense phase pneumatic conveying of powders. The pressure behaviour of the gas flow in the top section of the pipeline was found to exhibit pulsatile oscillations. In particular, the pulse velocity showed variation in magnitude while the frequency of the oscillations rarely exceeded 5 Hz. A wavelet analysis using the Daubechie 4 wavelet found that the amplitude of the oscillations increased along the pipeline. Furthermore, there was significant variation in gas pulse amplitude for different types of particulate material.

关键词： pneumatic conveying Powders Dense phase Pulsatile flow Transient flow

An assessment of steady-state conditions in single slug horizontal pneumatic conveying

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Particuology 2021年第5期19卷 187-195页

作者： A.Lavrinec O.Orozovic H.Rajabnia K.Williams M.G.Jones G.E.Klinzing Centre for Bulk Solids and Particulate Technologies The University of NewcastleNSW 2308Australia Department of Chemical and Petroleum Engineering The University of PittsburghPA 15261USA

This study used a 3D coupled CFD–DEM model to assess how slugs tend towards steady state in single slug horizontal pneumatic conveying.Initial slug length,inlet velocity and initial stationary layer fractions were systematically varied for a total of 72 simulations.Previously made observation that slugs tend towards a steady state was confirmed via a theoretical derivation.The derivation shows that slugs move towards their steady state lengths exponentially.This allowed for a calculation of a characteristic time scale which is a measure of how quickly a slug tends towards the steady state.The theoretical estimate which is a function of slug porosity,steady length,velocity and stationary layer fraction has good agreement with simulated results.A link between steady slug length and solids loading ratio was also shown.

关键词： pneumatic conveying Dense phase Slug flow Steady state

Experimental study of the blockage boundary for dense-phase pneumatic conveying of powders through a horizontal slit

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Particuology 2015年第4期13卷 128-134页

作者： Shengyong Hu Fubao Zhou Yingke Liu Jianhong Kang Yifan Zhang Tongqiang Xia Faculty of Safety Engineering China University of Mining and Technology College of Mining Technology Taiyuan University of Technology Key Laboratory of Gas and Fire Control for Coal Mines China University of Mining and Technology

The estimation of the blockage boundary for pneumatic conveying through a slit is of significant importance. In this paper, we investigate the characteristics for blockage of powder （48 gLm average diameter） through a horizontal slit （1.6 m × 0.05 m × 0.002 m）. The results show that the required critical solid mass flow rate increases as the superficial air velocity increases superficial air velocity. The solid loading ratio and superficial air velocity displayed a decreasing power law relationship. This finding agrees with existing theory and experimental results. However, a minimum inlet solid loading ratio exists. When the air velocity is greater than the corresponding air velocity of the minimum solid loading ratio, the solid loading ratio exhibits an increasing trend in power law. We also found that when the inlet conveying pressure increased, the critical solid mass flow rate required for blockage, the inlet solid loading ratio, and the minimum inlet solid loading ratio increased.

关键词： Dense phase pneumatic conveying Blockage boundaw Horizontal slit

Numerical and experimental study of an innovative pipeline design in a granular pneumatic-conveying system

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Particuology 2018年第3期16卷 196-203页

作者： Hasan Ghafori Hamid Reza Ebrahimi Department of Mechanical Engineering MaJlesi Branch Islamic Azad University lsfilhan Iran Department of Chemical Engineering Majlesi Branch Islamic Azad University lsfahan Iran

During gas-solid mixture conveying in a dense phase, material is conveyed in dunes on the bottom of the pipeline, or as a pulsating moving bed. This phenomenon increases the pressure drop and power consumption. We introduce a new technique to reduce the pressure drop, which is termed the perforated double tube. To validate this new model, the gas-solid flow pattern and pressure drop were studied numerically and experimentally. The power consumption was also studied experimentally. Numerical studies were performed by the Eulerian-Lagrangian approach to predict gas and particle movement in the pipeline, Comparisons between the numerical predictions and the experimental results for the gas-solid flow patterns and pressure drop show good agreement.

关键词： Computational fluid dynamics Power consumption Perforated double tube pneumatic conveying