碳化硅浓悬浮体的分散特性和流变性研究

通过对碳化硅粉体在有机单体介质中的Zeta电位，分散剂用量和浓悬浮体的粘度等的测试及其沉降试验，详细研究了粒径分布较宽的碳化硅粉体（0.2-250μm)的胶体分散特性，沉降行为以及浓悬浮体的流变行为。结果表明，选用适量的分散剂四甲基氢氧化铵可使SiC颗粒的Zeta电位绝对值提高近20mV，调整浆料pH至11．9附近可制备出固相体积分数高达70％的SiC浓悬浮体。该浓悬浮体中粗细SiC颗粒间能达到一稳定的分数，悬浮粒子不会产生明显地沉降，其流变行为符合Quemada模型。     

无机悬浮颗粒的混凝特性和絮凝体形态学研究

研究了絮凝体的形成过程及其形态学特性.结果表明,无机悬浮颗粒体系的最佳混凝pH值在7～8之间,在低投药量时,压缩双电层和吸附电中和是主要的混凝机理,在高投药量条件下,则是卷扫絮凝起主导作用.絮凝体平均粒径和分形维数都随搅拌时间的延长而增大,并最终趋于稳定.在pH=7和以硫酸铝作为混凝剂的条件下,形成的絮凝体最大粒径为0.3mm,对应的分形维数在1.78左右.随着投药量的增大,絮凝体分形维数的变化较小,但絮凝体平均粒径显著增加;当投药量过高时,网扫絮凝作用下的絮体结构松散,抗剪切能力差,具有较小的平均粒径和分形维数.     

单颗粒/液滴燃料悬浮燃烧研究进展

总结并对比了气动悬浮、电动悬浮、磁悬浮、光悬浮和声悬浮这5种常重力环境下悬浮技术的特点,在此基础上综述了近年来固体燃料颗粒以及液体燃料液滴的悬浮燃烧研究进展。指出悬浮燃烧技术消除了样品和载体之间的接触热传导,有利于从微观尺度上准确描述燃烧过程中物质的变化和能量的释放规律,获取物质的本征燃烧特性。在多种悬浮技术中光镊悬浮具有材料适用范围广、可精确操控颗粒/液滴悬浮位置、悬浮稳定性好以及便于集成等优点,是含能材料燃烧领域中最具有应用前景的一种。未来工作中建议加强单颗粒/液滴燃烧过程产物化学组成表征、扩展悬浮燃烧技术在含能材料领域中的应用范围以及开展含能材料多颗粒、多液滴的燃烧特性及相互作用机理研究。附参考文献44篇。     

浓相气力输送技术在精细化工行业中的应用研究

浓相气力输送系统具有输送效率高、能耗低、管道磨损小等优点,被广泛应用于各行各业。根据精细化工行业涉及到的物料特点和生产要求,针对一些特殊散装固体物料的输送处理和计量精度,简要介绍了一种采用球型混合器的新型浓相发送罐的组件、工作原理、功能特点,以及在精细化工行业中的应用实例,认为该浓相气力输送技术对提高生产效率、加强环保效果起到了重要作用。     

赤道东太平洋海洋悬浮体浓度研究

本研究基于2011年大洋一号第22次环球考察在东太平洋热液活动区采集的5个站位的77个悬浮体样品,通过测量以滤膜为载体的悬浮物质含量,测定了水体中悬浮体的浓度。结果显示东太平洋热液活动区各站悬浮体浓度较低,在0.01-0.58mg/L之间,各站各层位间分布不均匀,总体表现为表层最高、底层较高、中层最低的特点。     

离子交换树脂珠体悬浮聚合技术探讨

对苯乙烯－ 二乙烯苯悬浮共聚制离子交换树脂珠体进行研究,探讨了各种因素对珠体粒径的影响。     

脉冲电场对海水中悬浮颗粒物沉降效率的影响

首次研究了海水中悬浮颗粒物在脉冲电场作用下的沉降效率,并对其影响机理进行了初步探讨.正交试验结果表明:影响海水中悬浮颗粒物沉降效率的因素顺序为脉冲电压、脉冲时间、脉冲处理次数、脉冲频率;且在各因素中较佳的水平条件下,沉降效率可达到86.4%,比未施加脉冲电场时提高近30%.TEM分析结果表明:在脉冲电场的作用下,海水中难沉降的带电荷悬浮颗粒物重新分布其所带电荷并导致偶极化,从而促进了颗粒物之间的凝聚.     

采出水中模拟悬浮颗粒沉降规律研究

采用已知大小的碳酸钙固体颗粒模拟新疆油田采出水中的悬浮颗粒,研究了颗粒沉降规律及影响因素,实验结果表明,影响颗粒沉降的主要因素是絮凝剂,其次是p H值和离子强度。低浓度絮凝剂(20 mg/L)存在条件下,颗粒沉降速率及沉降效率即有显著提高,浓度越大,效果越明显;随着p H值的增大,颗粒沉降速率及沉降效率同样有明显提高;低矿化度条件下(500 mg/L),颗粒沉降速率几乎无变化,矿化度达到2 000mg/L时有较为明显提高;钙镁离子浓度的影响等同于矿化度的影响;聚合物整体上会促进颗粒的沉降,达到净化效果,但由于聚合物溶液存在一定粘度导致颗粒沉降规律变化较为复杂。     

防沉降性铝酸酯在含填料环氧树脂浇铸体中的应用

本文报告了防沉降性铝酸酯(Anti—settling Aluminate,简称ASA)在环氧树脂/填料浇铸体中的应用。研究了ASA对轻质碳酸钙、石墨和铝粉等填料在环氧树脂中温固化时的防沉降作用,并对防沉降效果进行了评价。文中还对ASA的降粘作用进行了研究。     

在无机分散剂存在下苯乙烯悬浮聚合宏观成粒的特征

以苯乙烯悬浮聚合为体系,考察羟基磷酸钙(HAP)或HAP与聚乙烯醇(PVA)复合为分散剂体系时,各种因素如分散剂浓度、油水比、搅拌速度等与瞬时液滴大小及分布之间的关系,并分析讨论瞬时液滴分散、合并的过程特征.结果表明,悬浮苯乙烯液滴聚合宏观成粒的特征与分散剂的分散机理无关,仅体现液滴分散、合并的过程特点.当采用分批加分散剂时,实验观察到瞬时液滴大小分布呈由单峰过渡到双峰,再发展成单峰分布的特征,从而找出了以分批加分散剂方式制备窄分布聚合物颗粒的理论依据.     

MACROPROCESS OF PARTICLE FORMATION IN SUSPENSION POLYMERIZATION OF STYRENE WITH INORGANIC STABILIZER SYSTEM

The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used.Those items such as the effects of the Weight fraction of dispersed-phase,the amount of the inorganic stabilizer and the agitation speed on the breakup and coalescence of thetransient dispersed drops etc.Were examined.Results showd that the dynamic behavior of the transi-ent polymer droplets changed in the presence of the suspension stabilizer during the reaction.     

悬浮法成型UP微粒粒径及其分布的控制

以不饱和聚酯树脂（UP）为原料,采用悬浮成型方法制备了粒径为120～250μm的UP球形微粒,从工艺控制的角度考察了搅拌速度、搅拌器形式及反应嚣形式对UP微粒平均粒径及粒径分布的影响。结果表明,将搅拌速度控制在500～1000r／min,以4口圆柱形烧瓶为反应器,采用双层平桨、且桨叶间距为4．5cm时,所制UP微粒的粒径最小、且粒径分布最窄。     

颗粒粒度分布对高固相含量氧化铝浆料流变性能的影响

制备了低粘度、高固相含量氧化铝悬浮浆料,并将其有效地应用于原位凝固胶态成型工艺中.将中位粒径尺寸分别为0.3μm和2.2 μm的2种氧化铝以不同级配混合后制得的粉体配制浆料.研究了氧化铝粉体颗粒度分布对高固含量氧化铝悬浮浆料流变性的影响.实验结果表明:混合粉体制成的悬浮液表现出不同的流变性.由细颗粒粉体制备的浆料表现出剪切稀化行为,但随着粗颗粒含量的增加,浆料逐渐向剪切厚化转变,依次呈现出Casson型、Bingham型、Herschel-Bulkey型3种不同的流变学特征,并得出了各自相应的流变学模型方程.讨论了流变模型转变的原因及其对胶态成型工艺的影响.粉体经级配后,当中位径d50＜1μm时,浆料呈现出触变性,并且触变性随着颗粒度的减小而增大.体积分数(下同)为58%固相含量的级配浆料的粘度较50%固含量的未级配浆料下降了7至10倍,明显改善了浆料的流变性,适合于原位凝固胶态成型工艺.     

THE EFFECT OF VISCOSITY ON PARTICLE SUSPENSION IN AN AERATED STIRRED VESSEL WITH DIFFERENT IMPELLERS AND BASES

The agitator speed required to suspend solids under gassed conditions, N _JSg , has been studied in water and in corn syrup of 0.01 and 0.1 Pas giving Reynolds numbers from the full turbulent region down to ～10³. Of the impellers tested, the down-pumping, three-blade, axial flow hydrofoil impellers are generally unsuitable for this duty, and although six-blade, mixed flow down-pumping impellers require the lowest mean specific energy dissipation rates to suspend the solids, (? _T ) _JSg , at low gas flow rates, they are still prone to flow instabilities and torque fluctuations. The latter poor characteristics are made worse by reducing the size of the impeller relative to the vessel and by increasing viscosity and gas flow rate, Q _GV . Thus, they are of limited use for such systems. The Ekato InterMIG impeller has the highest (? _T ) _JSg and tends to cause vessel vibrations when dispersing the gas, and this weakness is also enhanced by increasing viscosity and gas flow rate. Again, they are generally not appropriate for three-phase systems. The radial flow Rushton turbine is quite stable and able to suspend the solids in all the fluids. However, it requires the second highest (? _T ) _JSg , and both (? _T ) _JSg and N _JSg increase substantially with increasing Q _GV . The up-pumping six-blade, mixed flow impeller of approximately half the vessel diameter is able to suspend the solids and is very stable in all the fluids. In addition, both (? _T ) _JSg and N _JSg are very insensitive to Q _GV , with (? _T ) _JSg generally being the lowest at the highest Q _GV . It is thus the preferred agitator among those tested. As in ungassed systems, modifying the base of the vessel can significantly lower (? _T ) _JSg and N _JSg for a given impeller type in water compared to a flat base. The concept of keeping constant torque as a means of maintaining suspension has been tested and found not to be valid in this work. Another approach to generalizing the results is also suggested.     

SUSPENSION CHARACTERISTICS OF LARGE CYLINDERS IN AGITATED TANKS

Considerable research has been done concerning solid suspension in agitated tanks. Typically, such studies concern slurries or granular material, such as sand, and involve minimum suspension rotational speeds or suspension homogeneity.

The objectives of this work are similar, however we are concerned with rather large cylinders of varying length to diameter ratios. The work involves: 1) the determination of minimum impeller rotational speed for suspension similar to criterion used by Zwietering, 2) the measurement of suspension heights and times, 3) an investigation into whether the correlations by Zwietering, Kolar and Rieger et al., can be used for predicting minimum suspension rotational speed and 4) weight fraction effects on minimum suspension rotational speed.     

SUSPENSION CHARACTERISTICS OF LARGE CYLINDERS IN AGITATED TANKS

Considerable research has been done concerning solid suspension in agitated tanks. Typically, such studies concern slurries or granular material, such as sand, and involve minimum suspension rotational speeds or suspension homogeneity.

The objectives of this work are similar, however we are concerned with rather large cylinders of varying length to diameter ratios. The work involves: 1) the determination of minimum impeller rotational speed for suspension similar to criterion used by Zwietering, 2) the measurement of suspension heights and times, 3) an investigation into whether the correlations by Zwietering, Kolar and Rieger et al., can be used for predicting minimum suspension rotational speed and 4) weight fraction effects on minimum suspension rotational speed.     

振动重介质流化床细粒焦渣混合物的分选

在间歇振动流化床中研究了细粒焦渣混合物的分离．通过考察细粒焦、细粒渣及细粒焦渣混合物的入选体积量对床层密度和分选效率的影响,得出适宜的操作条件．在此条件下对细粒焦渣混合物进行了分选实验,得到了较佳的分离效率。     

ON THE RHEOLOGY OF THE DENSE PHASE OF A GAS FLUIDISED BED

Measurements of bubble rise velocities in two gas fluidised beds have been compared with numerical simulations of spherical bubble-wake regions rising through Newtonian liquids. The comparisons have been used to elucidate the rheological nature of the dense phase of gas fluidised beds. The investigation sheds new light upon results obtained in the past by other workers, who did not have the benefit of the powerful numerical simulation techniques of today

It was found that the assumption of a Newtonian viscosity coefficient of 0.8 Pa s (values around this have often been suggested in the literature) yields bubble rise velocities of the right order of magnitude. Nevertheless, the experimentally determined variation in bubble rise velocity with size cannot be explained fully on basis of a Newtonian rheological model, but indicates shear-thickening behaviour of the dense phase. A discussion, also of the effect of bubble Reynolds number and wall effects upon the dense phase flowpaltern around rising bubbles, and comparison with other work is provided.     

蒙脱石的溶胀、蒙脱石-水悬浮液及悬浮乳液的流变特性

采用水悬浮法对蒙脱石原土进行钠离子交换反应和提纯处理得到纯度较高的钠型蒙脱石。研究了钠型蒙脱石在水中的溶胀行为。用MC-1粘度仪研究了蒙脱石-水悬浮液的流变特性,考察了蒙脱石的固相含量、在水中的溶胀时间以及电解质对悬浮液流变行为的影响。研究发现：当固相含量较低（≤3．0％,质量分数,下同）时,悬浮液为Newton流体,随着蒙脱石含量的提高（≥5．0％）,悬浮液由Newton流体向假塑性流体转变。根据蒙脱石含量的不同,蒙脱石在水中的溶胀剥离需要数小时到数十小时不等,而超声波分散处理使蒙脱石溶胀剥离的时间缩短到10min左右。向蒙脱石-水悬浮液中加入电解质NaCl会导致蒙脱石的片层聚并在一起并形成网络结构,悬浮液的粘度特别是在低剪切速率下的粘度有数倍的增加。对不同固-液分散相比例的悬浮乳液的流变性能测定表明：蒙脱石片层双电层与乳液液滴的双电层之间存在相互作用,导致悬浮乳液产生独特的粘度变化。