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Solid–liquid equilibrium of dimethyl terephthalate(DMT), dimethyl isophthalate(DMI) and dimethyl phthalate(DMP) in melt crystallization process

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Chinese Journal of Chemical Engineering 2017年第12期25卷 1735-1739页

作者： Chunyuan Wu youwei cheng Lijun Wang Xi Li Department of Chemical and Biological Engineering Zhejiang University Hangzhou 310027 China

The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The result demonstrated DMT/DMI and DMT/DMP systems are eutectic while DMI/DMP is a solid-solution system. The eutectic temperature of DMT/DMI system is 336.7 K and that of DMT/DMP is 271.1 K. Furthermore, a classical solid-liquid phase equilibrium model was used to fit the experimental data of the eutectic systems of DMT/DMI and DMT/ DMP and the theoretical model could describe the eutectic solid-liquid phase diagrams properly.

关键词： Solid-liquid equilibrium Differential scanning calorimetry Eutectic Solid-solution Phase equilibrium model

Experimental and numerical investigations of scale-up effects on the hydrodynamics of slurry bubble columns

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Chinese Journal of Chemical Engineering 2016年第8期24卷 963-971页

作者： Zhaoqi Li Xiaoping Guan Lijun Wang youwei cheng Xi Li Department of Chemical and Biological Engineering Zhejiang University

Experiments and simulations were conducted for bubble columns with diameter of 0.2 m(180 mm i.d.), 0.5 m(476 mm i.d.) and 0.8 m(760 mm i.d.) at high superficial gas velocities(0.12–0.62 m·s-1) and high solid concentrations(0–30 vol%). Radial profiles of time-averaged gas holdup, axial liquid velocity, and turbulent kinetic energy were measured by using in-house developed conductivity probes and Pavlov tubes. Effects of column diameter, superficial gas velocity, and solid concentration were investigated in a wide range of operating conditions. Experimental results indicated that the average gas holdup remarkably increases with superficial gas velocity, and the radial profiles of investigated flow properties become steeper at high superficial gas velocities. The axial liquid velocities significantly increase with the growth of the column size, whereas the gas holdup was slightly affected. The presence of solid in bubble columns would inhibit the breakage of bubbles, which results in an increase in bubble rise velocity and a decrease in gas holdup, but time-averaged axial liquid velocities remain almost the same as that of the hollow column. Furthermore, a 2-D axisymmetric k–ε model was used to simulate heterogeneous bubbly flow using commercial code FLUENT 6.2. The lateral lift force and the turbulent diffusion force were introduced for the determination of gas holdup profiles and the effects of solid concentration were considered as the variation of average bubble diameter in the model. Results predicted by the CFD simulation showed good agreement with experimental data.

关键词： Bubble column CFD Hydrodynamics Multiphase flow Scaling-up Solid concentration

A new high-pressure die casting Mg-Gd-Sm-Al alloy with high strength-ductility synergy

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Journal of Rare Earths 2024年第12期42卷 2239-2248页

作者： Shuhui Lv youwei cheng Bo Deng Tao Xu Xin Qiu Qiang Yang School of Materials Science and Engineering Changchun University of Science and Technology State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Kashui International Holdings Limited

A high-pressure die casting（HPDC） Mg-5Gd-1.5Sm-0.7Al alloy was newly developed and exhibits outstanding strength-ductility synergy, with the yield strength and the tensile elongation to fracture being approximately 200 MPa and 8.5%, respectively. This alloy has two types of a-Mg grains: coarse a1-Mg(（46 ± 18） μm) and fine a2-Mg(（9.2 ± 2.3） μm) grains, and various Al-GS（GS = Gd and Sm） particles located at grain boundaries while clear solute-atom segregation near grain boundaries with limited or free intermetallic particles. Characterizations using Cs-corrected high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） indicate the crystal structures of Al-GS phases. After aging, dense β'precipitates and chain-shaped β''-like structures precipitated near grain boundaries while a high density of ultrafine β''-（Mg,Al）3Sm precipitates and Al-GS clusters formed in grain center. Relatively fine grains, Al-GS primary particles, solute-atom segregation near grain boundaries, and/or multiple precipitates contribute to the high strength of the studied alloy, while the multi-scale a-Mg grains,variety of intermetallic particles but discontinuous skeleton, and the multi-typed precipitated lead to its satisfactory ductility.

关键词： magnesium alloys strength-ductility synergy intermetallic phases scanning/transmission electron microscopy (STEM) precipitate rare earths

Light olefin production by catalytic co-cracking of Fischer–Tropsch distillate with methanol and the reaction kinetics investigation

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Chinese Journal of Chemical Engineering 2020年第1期28卷 143-151页

作者： Hui Zou Teng Pan Yanwen Shi youwei cheng Lijun Wang Yu Zhang Xi Li Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China Institute of Zhejiang University Jiuhua Boulevard NorthQzhou 324000China Ningxia Shenyao Technology Co. Ltd.China Energy Investment Co.West Desheng Road 1Yinchuan 750200China

Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.

关键词： Fischer–Tropsch distillate Catalytic co-cracking Light olefins Methanol Reaction kinetics

Progress in the research and development of p-xylene liquid phase oxidation process

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Frontiers of Chemical Science and Engineering 2007年第3期1卷 317-326页

作者： WANG Lijun cheng youwei WANG Qinbo LI Xi College of Material Science and Chemical Engineering Zhejiang UniversityHangzhou 310027China

The process of p-xylene liquid phase oxidation to produce purified terephthalic acid(PTA)involves a series of liquid phase radical reactions,chemical absorption,reac-tive crystallization,and evaporation.A commercial PTA production flow sheet includes a number of unit operations,which construct a complex process *** this paper,a review of research and development(R&D)works on PTA process carried out in Zhejiang University during recent years is *** works cover the oxidation and crystallization kinetics,gas-liquid mass transfer and evaporation,reactor modeling,database development,novel reactor design,process modeling,simulation,and *** author emphasizes the viewpoint through this case study that chemical reaction engineering should be developed to process system engineering to extend its scope,and particular attention should be paid on reactor and process modeling.

关键词： p-xylene oxidation terephthalic acid chemical kinetics reactor modeling process optimization

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光纤法颗粒速度测量信号的标定与校正

化学反应工程与工艺 2013年第2期29卷 105-110页

作者：吴诚高希成有为李希浙江大学化学工程与生物工程学系浙江杭州310027

使用PV6D颗粒速度测量仪测量了流化床中的颗粒速度并进行信号分析。制作圆盘速度标定装置校正由光纤互相关计算得到的颗粒速度。考察了被测物体运动速度以及测量间距对光纤测得速度和信号强度的影响。实验证明:距探头4 mm以外的信号是... 详细信息

使用PV6D颗粒速度测量仪测量了流化床中的颗粒速度并进行信号分析。制作圆盘速度标定装置校正由光纤互相关计算得到的颗粒速度。考察了被测物体运动速度以及测量间距对光纤测得速度和信号强度的影响。实验证明:距探头4 mm以外的信号是造成测量偏差的主因,而被测物体运动速度对测量结果影响不大。根据标定实验得到速度偏离曲线和信号衰减曲线,分析了原始信号中造成速度偏离的远距离信号占信号总体的比率。将按照不同阈值滤波后计算所得速度进行对比,并评估数据失真程度,提出了一种利用滤波阈值进行颗粒速度校正的方法,并筛选出适合本实验条件的滤波阈值。

关键词：流化床颗粒速度校正光纤

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甲醇降解碱木质素

化学反应工程与工艺 2012年第2期28卷 129-137页

作者：陈啸成有为李希浙江大学化学工程与生物工程学系浙江杭州310027

采用超临界甲醇法将碱木质素降解为小分子芳香族化合物,考察了反应温度、反应时间和溶剂中水含量对降解反应的影响。碱木质素被降解为约21种单环芳香族化合物,其中7～11种为主要组分,多为以愈创木基结构为主的芳香族衍生物。产物中非酚... 详细信息

采用超临界甲醇法将碱木质素降解为小分子芳香族化合物,考察了反应温度、反应时间和溶剂中水含量对降解反应的影响。碱木质素被降解为约21种单环芳香族化合物,其中7～11种为主要组分,多为以愈创木基结构为主的芳香族衍生物。产物中非酚型组分较稳定,不易发生进一步反应,且随着反应时间的延长,其所占比例不断增大,而酚型组分稳定性较差,易发生进一步反应。碱木质素降解反应速率的突变发生在250～280℃,温度越高,反应速率越大。水的存在有利于醚键的断裂和酚型组分的生成。在水体积分数为50%的甲醇-水共溶剂体系中,2-甲氧基-4-乙基苯酚的选择性最好,其在产物中的质量分数达48.6%。碱木质素的醚键在反应中全部断裂,四氢呋喃不溶物中主要是以缩合结构为主的木质素残片和再聚合产物。

关键词：碱木质素甲醇水共溶剂体系

湍动流化床过渡段固含率分布特征的实验及数值模拟

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化工学报 2013年第3期64卷 858-866页

作者：吴诚高希成有为王丽军李希浙江大学化学工程与生物工程学系浙江杭州310027

在湍动流化床中,过渡段对于包括甲醇制烯烃在内的气固催化快反应有着重要的作用。采用PV6D反射型光纤探针对内径95mm的湍动流化床内过渡段的固含率分布和脉动参数进行了测量,分别考察了表观气速和静床高的影响,并采用修正的基于颗粒动... 详细信息

在湍动流化床中,过渡段对于包括甲醇制烯烃在内的气固催化快反应有着重要的作用。采用PV6D反射型光纤探针对内径95mm的湍动流化床内过渡段的固含率分布和脉动参数进行了测量,分别考察了表观气速和静床高的影响,并采用修正的基于颗粒动力学的三段曳力双流体模型进行模拟。实验表明,湍动流化床过渡段中固含率的轴向分布呈现S型和指数型两种类型,固含率轴向与径向分布都在过渡段内出现最大梯度,表明过渡段中固体浓度分布比稀相段和密相段更不均匀。表观气速和静床高的变化将导致S型和指数型分布的相互转变,并且对过渡段底部与壁面附近的固体高浓度区影响最为显著。局部固含率脉动概率密度分布表明,在静床高较小时,随着气速的增大,床层下部气含率最大值位置将从中心区移动至环隙区,呈现气含率的双峰型分布。本文提出的修正三段曳力模型考虑了颗粒团聚的影响,对过渡段中分布板影响区之外的固含率分布均能较好地模拟。

关键词：湍动流化床过渡段光纤测量固含率分布计算流体力学

对苯二甲酸氧化残渣中的有色杂质在活性炭上的吸附规律

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化学反应工程与工艺 2009年第6期25卷 566-570页

作者：郭霞成有为李希浙江大学材料与化学工程学院浙江杭州310027

为了去除对苯二甲酸氧化残渣中的有色杂质,考察了活性炭类型、吸附温度及溶剂体系含水量对吸附过程的影响。结果表明:以二甲基亚砜作为溶剂的吸附体系中,有色杂质在活性炭上的吸附遵循Langmuir吸附规律;不同类型的活性炭AC-1(木质)与AC... 详细信息

为了去除对苯二甲酸氧化残渣中的有色杂质,考察了活性炭类型、吸附温度及溶剂体系含水量对吸附过程的影响。结果表明:以二甲基亚砜作为溶剂的吸附体系中,有色杂质在活性炭上的吸附遵循Langmuir吸附规律;不同类型的活性炭AC-1(木质)与AC-2(煤质)的吸附性能具有不同的温度敏感性,温度对AC-2影响更显著;在溶剂体系中加少量的水有利于杂质吸附。

关键词：对苯二甲酸固体残渣吸附活性炭