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Investigation of the segregation of a binary particle mixture in a square circulating fluidized bed with air staging

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Particuology 2019年第6期17卷 70-76页

作者： Mingkun Du Shuai Wang Guangdong Institute of special equipment inspection and Research Zhuhai Inspection InstituteZhuhai 519002China School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

To further understand the segregation characteristics of a binary particle mixture in a riser,the flow behaviors of particles with different sizes were experimentally and numerically investigated in a cold square circulating fluidized *** impact of the gas velocity,solid circulation rate,initial coarse particle fraction,and air staging on the coarse particle fraction and axial pressure drop were *** experimental results show that air staging can significantly promote the pressure drop of a binary mixture at the bottom of the bed compared with that of monosized ***,the segregation of the binary mixture at the bottom is *** was also found that there was clear radial segregation owing to a higher coarse particle fraction near the wall compared with the bed's center and its corner.

关键词： Circulating fluidized bed Binary mixture Segregation Air staging

Experimental Analysis of Radial Centrifugal Pump Shutdown

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Fluid Dynamics & Materials Processing 2024年第4期20卷 725-737页

作者： Xiao Sun Jiangbo Tong Yuliang Zhang Haibing Cai Wen Zhou Xiaoqi Jia Litao Ou School of Mechanical Engineering Hunan University of TechnologyZhuzhou412007China College of Mechanical Engineering Quzhou UniversityQuzhou324000China Zhejiang Testing&inspection Institute for Mechanical and Electrical Products Quality Co. Ltd.Hangzhou310014China quzhou special equipment inspection center Quzhou324000China The Zhejiang Provincial Key Lab of Fluid Transmission Technology Zhejiang Sci-Tech UniversityHangzhou310018China Zhuzhou Nanfang Valve Co. Ltd.Zhuzhou412000China

Centrifugal pumps are widely used in the metallurgy,coal,and building *** order to study the hydraulic characteristics of a closed impeller centrifugal pump during its shutdown in the so-called power frequency and frequency conversion modes,experiments were carried to determine the characteristic evolution of parameters such as speed,inlet and outlet pressure,head,flow rate and shaft power.A quasi-steady-state method was also used to further investigate these transient *** results show that,compared to the power frequency input,the performance parameter curves for the frequency conversion input are less volatile and *** characteristic time is longer and the response to shutdown is *** quasi-steady-state theoretical head-flow curves match the experimental head-flow curves more closely at low flow rates when the frequency conversion input is ***,in this case,the similarity law predicts the hydraulic performance more accurately.

关键词： Centrifugal pump power frequency frequency conversion shutdown external characteristic experimental study

Effect of void size and Mg contents on plastic deformation behaviors of Al-Mg alloy with pre-existing void:Molecular dynamics study

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Chinese Physics B 2022年第6期31卷 580-588页

作者： Ning Wei Ai-Qiang Shi Zhi-Hui Li Bing-Xian Ou Si-Han Zhao Jun-Hua Zhao Jiangsu Key Laboratory of Advanced Food Manufacturing equipment and Technology Jiangnan UniversityWuxi 214122China China Aerodynamics Research and Development center Mianyang 621000China National Laboratory for Computational Fluid Dynamics Beijing 100191China National Graphene Products Quality Supervision and inspection center Special Equipment Safety Supervision Inspection Institute of Jiangsu ProvinceWuxi 214174China

The plastic deformation properties of cylindrical pre-void aluminum-magnesium(Al-Mg)alloy under uniaxial tension are explored using molecular dynamics simulations with embedded atom method(EAM)*** factors of Mg content,void size,and temperature are *** results show that the void fraction decreases with increasing Mg in the plastic deformation,and it is almost independent of Mg content when Mg is beyond 5%.Both Mg contents and stacking faults around the void affect the void *** phenomena are explained by the dislocation density of the sample and stacking faults distribution around the *** variation trends of yield stress caused by void size are in good agreement with the Lubarda ***,temperature effects are explored,the yield stress and Young’s modulus obviously decrease with *** results may enrich and facilitate the understanding of the plastic mechanism of Al-Mg with defects or other alloys.

关键词： Al-Mg alloys molecular dynamics nanovoid plastic deformation

Defects detection in typical positions of bend pipes using low-frequency ultrasonic guided wave

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Journal of Central South University 2015年第10期22卷 3860-3867页

作者：罗更生谭建平汪亮许焰 School of Mechanical and Electrical Engineering Central South University Hunan Provincial special equipment inspection and Research Institute center of Public Courses Zhuhai College of Jilin University Department of Mechanical and Electrical Engineering Changsha University

In order to analyze the possibility of detecting defects in bend pipe using low-frequency ultrasonic guided wave, the propagation of T(0,1) mode and L(0,2) mode through straight-curved-straight pipe sections was studied. FE(finite element) models of bend pipe without defects and those with defects were introduced to analyze energy distribution, mode transition and defect detection of ultrasonic guided wave. FE simulation results were validated by experiments of four different bend pipes with circumferential defects in different positions. It is shown that most energy of T(0,1) mode or L(0,2) mode focuses on extrados of bend but little passes through intrados of bend, and T(0,1) mode or L(0,2) mode is converted to other possible non-axisymmetric modes when propagating through the bend and the defect after bend respectively. Furthermore, L(0,2) mode is more sensitive to circumferential notch than T(0,1) mode. The results of this work are beneficial for practical testing of pipes.

关键词： low-frequency ultrasonic guided wave bend pipe extrados of bend intrados of bend FE(finite element) simulation experimental investigation

A granular-biomass high temperature pyrolysis model based on the Darcy flow

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Frontiers of Earth Science 2015年第1期9卷 114-124页

作者： Jian GUAN Guoli QI Peng DONG China special equipment inspection and Research Institute Beijing 100013 China School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China

We established a model for the chemical reaction kinetics of biomass pyrolysis via the hightemperature thermal cracking of liquid products. We divided the condensable volatiles into two groups, based on the characteristics of the liquid prdoducts., tar and biomass oil. The effects of temperature, residence time, particle size, velocity, pressure, and other parameters on biomass pyrolysis and high-temperature tar cracking were investigated numerically, and the results were compared with experimental data. The simulation results showed a large endothermic pyrolysis reaction effect on temperature and the reaction process. The pyrolysis reaction zone had a constant temperature period in several layers near the center of large biomass particles. A purely physical heating process was observed before and after this period, according to the temperature index curve.

关键词： biomass pyrolysis high temperature pyrolysis model condensable volatile cracking Darcy flow

Atomistic simulations on adhesive contact of single crystal Cu and wear behavior of Cu-Zn alloy

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Chinese Physics B 2021年第2期30卷 442-448页

作者： You-Jun Ye Le Qin Jing Li Lin Liu Ling-Kang Wu National Quality Supervision and inspection center of Pressure Pipe Components Special Equipment Safety Supervision Inspection Institute of Jiangsu ProvinceNanjing 210036China School of Mechanical Engineering Changzhou UniversityChangzhou 213164China Jiangsu Power equipment Co. LtdChangzhou 213000China School of Material Science and Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332-0245USA

Atomistic simulations are carried out to investigate the nano-indentation of single crystal Cu and the sliding of the Cu-Zn *** the contact zone is extended due to adhesive interaction between the contact atoms,the contact area on a nanoscale is redefined.A comparison of contact area and contact force between molecular dynamics(MD)and contact theory based on Greenwood-Williamson(GW)model is *** roughness causes the adhesive interaction to weaken,showing the better consistency between the calculated results by MD and those from the theoretical *** simulations of the sliding show that the substrate wear decreases with the mol%of Zn increasing,due to the fact that the diffusion movements of Zn atoms in substrate are blocked during the sliding because of the hexagonal close packed(hcp)structure of Zn.

关键词： atomistic simulation nano-indentation wear behavior

Simulation of gas-solid flow characteristics of the circulating fluidized bed boiler under pure-oxygen combustion conditions

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Chinese Journal of Chemical Engineering 2024年第6期70卷 9-19页

作者： Kaixuan Gao Xiwei Ke Bingjun Du Zhenchuan Wang Yan Jin Zhong Huang Yanhong Li Xuemin Liu Key Laboratory of special equipment Safety and Energy-Saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China School of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuan 030024China

Under the pressure of carbon neutrality,many carbon capture,utilization and storage technologies have witnessed rapid development in the recent years,including oxy-fuel combustion(OFC)***,the conventional OFC technology usually depends on the flue gas recirculation system,which faces significant investment,high energy consumption,and potential low-temperature corrosion *** these deficiencies,the direct utilization of pure oxygen to achieve particle fluidization and fuel combustion may reduce the overall energy consumption and CO_(2)-capture *** this paper,the fundamental structure of a self-designed 130 t·h^(-1) pure-oxygen combustion circulating fluidized bed(CFB)boiler was provided,and the computational particle fluid dynamics method was used to analyze the gas-solid flow characteristics of this new-concept boiler under different working *** results indicate that through the careful selection of design or operational parameters,such as average bed-material size and fluidization velocity,the pure-oxygen combustion CFB system can maintain the ideal fluidization state,namely significant internal and external particle ***,the contraction section of the boiler leads to the particle backflow in the lower furnace,resulting in the particle suspension concentration near the wall region being higher than that in the center ***,the upper furnace still retains the classic core-annulus flow *** addition to increasing solid circulation rate by reducing the average bed-material size,altering primary gas ratio and bed inventory can also exert varying degrees of influence on the gas-solid flow characteristics of the pure-oxygen combustion CFB boiler.

关键词： Circulating fluidized bed Pure-oxygen combustion Gas-solid flow characteristics Simulation CO_(2)capture

Mechanical Properties and Wettability of Bagasse-reinforced Composite

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Journal of Wuhan University of Technology(Materials Science) 2019年第2期34卷 312-316页

作者：朱继元 XIONG Jingwen HU Xiaofang 王冰莹 College of Mechanical and Control Engineering Guilin University of Technology Guangzhou Academy of special equipment inspection & testing School of Mechanical&Automotive Engineering South China University of Technology Guangzhou Trust Engineering equipment Co. Ltd.

Bagasse fibers were modified using NaOH, KH550, and NaOH/KH550, respectively, and used as reinforcement to prepare bagasse/starch/PVA composite. A combination of Fourier-transform infrared(FTIR) spectroscopy and X-ray diffraction(XRD) was used to investigate the chemical composition. The surface of bagasse fibers and cross-sectional morphologies for bagasse/starch/PVA composite were also characterized by scanning electron microscopy(SEM). Contact angles were measured to test the wettability of the resulting composite. After the chemical treatment with NaOH/KH550, the mechanical properties of the composite can be greatly improved. The contact angle is larger, indicating the variation of surface property from hydrophilicity into hydrophobicity.

关键词： bagasse PVA mechanical properties contact angle hydrophobicity

Corrosion behavior of HVOF Inconel 625 coating in the simulated marine environment

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China Welding 2024年第1期33卷 46-51页

作者：彭超钟丰平袁梦谢世杰王学斌 National Quality inspection and Testing center of special Metal Structural Materials Zhejiang Academy of Special Equipment ScienceHangzhou 310020China Key Laboratory of special equipment Safety Testing Technology of Zhejiang Province Hangzhou 310020China Zhejiang-Ukraine Joint Laboratory for Materials and Welding Testing Technology Hangzhou 310020China

High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy *** 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF *** this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine *** experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating *** in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.

关键词： high velocity oxygen fuel(HVOF) Inconel 625 coating marine environment corrosion