激光全息干涉法测量液相质扩散系数数字图像处理的研究

用He-Ne激光器、CCD和图像采集系统等仪器设备,搭建了数字激光全息干涉法测量液相质扩散系数的实验系统,并测试获得了浓度为0.33 mol/l KCl水溶液在298.15 K温度下的全息干涉图像,采用了图像增强、全息干涉条纹图再现及相位展开等数字图像处理过程的关键技术对全息干涉图进行处理,得到了相位展开后物光相位差,经换算后获得了该溶液的质扩散系数.为化工工程上研究替代制冷荆急需的质扩散系数测量提供了有效的方法.     

基于干涉条纹极值点质扩散系数的数学描述

以费克第二定律为理论基础,依据半无限厚板中扩散过程的原理建立质扩散数学模型,并在模型中采用激光全息干涉实验方法测得干涉条纹极值参数,进而获得液液质扩散系数数学描述。测得温度为15℃时,浓度0．10mol／L的蔗糖溶液向水溶液中扩散产生的干涉条纹极值,计算出蔗糖溶液液相质扩散系数值,与文献值比较,其误差为3．67％,标准偏差为0．378,验证了基于干涉条纹极值点质扩散公式的准确性。为化工工程上研究替代制冷剂急需的质扩散系数的理论研究提供了有效的数学方法。     

数字全息干涉法测量液相质扩散系数的研究

介绍数字全息干涉法测量原理.设计并搭建基于数字全息干涉法和新的扩散槽测量质扩散系数的实验系统,并使用此系统测量了浓度为0.33 mol/l的KCl水溶液在温度为291.8、294.7、298.8、299.8、305.4、308.5、315.2 K条件下的质扩散系数,实验结果表明实验值和文献参考值之间相对偏差绝对值的平均数为1.3%,验证了试验系统的精确性和可靠性.最后,在此系统上测量了浓度为0.1 mol/1的蔗糖水溶液在288.15～338.15 K温度范围内的质扩散系数.为测量工程上急需新型燃料替代工质和新型制冷剂替代工质的质扩散系数提供了一种新的有效方法.     

数字全息法测量液相扩散系数实验研究

采用数字全息干涉法测量了25℃乙二醇-水物系的扩散系数。详细介绍了实验方法以及2种处理干涉图像获得扩散系数的方法,即横条纹法和弯条纹法。通过测量25℃时0.33 mol/L KCl溶液的扩散验证了实验的精确性。分别用2种方法获得了6个不同质量分数下的乙二醇-水物系的扩散系数,并与文献值进行了对比。结果表明,弯曲条纹法的平均相对偏差是1.3%,比水平条纹法的1.7%小,同时,弯曲条纹法的平均标准偏差更小,说明波动更小。     

从重整抽余油中提取正庚烷

正庚烷用途越来越广泛,但制取较为困难.通过实验对不同填料在分馏中的效果加以论述,从而找到一种比较好的分离方法,提取到较纯的正庚烷.     

氨基酸在水溶液中的扩散系数

There are still limited experimental data of liquid diffusion coefficients in literature. Therefore, the experimental investigation and prediction model are of practical and theoretical significance. The diffusion coefficients of L-serine, L-threonine, L-arginine, in aqueous solution at 298. 15 K were measured respectively by holographic interferometer. The affecting factors of molecular structure and polarity were analyzed and discussed. Finally, a modified semi-empirical model for correlating the diffusion coefficients of solid organic compounds in aqueous solutions at 298. 15 K was proposed with an adjustable parameter added. The average deviation between model prediction values and experimental ones is less than 0.2%, which shows a considerably satisfactory accuracy.     

激光全息干涉法测量功能糖醇在水溶液中的扩散系数

功能糖醇在医药和食品中得到广泛应用,其在水溶液中的扩散系数是相关研究与应用中最基本和最重要的物性参数之一,因此实验测定功能糖醇在水溶液中的扩散系数具有十分重要的意义.今采用实时激光全息干涉法,结合CCD图像采集和数字处理技术,测定了293.15 K下赤藓醇、木糖醇、山梨醇、甘露醇以及麦芽糖醇在水溶液中的扩散系数.实验结...     

高压氮气在正庚烷中溶解度的数学模型

采用R-K状态方程和正规溶液理论推导出高压氮气在正庚烷中的溶解度模型为lnX=lnP B1P B2P2 B3,并通过实验测定了其理论模型参数分别为:B1=-2.64 8.92×10-3T-5.06×10-6T2,B2=3.61×10-2 6.91×10-4T-2.18×10-6T2,B3=3.92-3.92×10-2T 5.20×10-5T2;在温度0~100℃与压力0~12 MPa范围内,经实验验证该模型计算值与实测数据平均相对偏差为-3.6%,因此该模型可以作为高压氮气在正庚烷中溶解度的适宜计算公式。     

从非芳组分中分离正庚烷的模拟研究

运用PROⅡ流程模拟软件对非芳组分按要求进行产品模拟切割,分离出较高纯度的正庚烷。并对两种模拟方案进行比较,找出能耗较低的分离流程,达到节能降耗的目的。同时通过实验过程来验证,表明模拟结果有一定的可信度。     

正庚烷在5A分子筛上的高温吸附/脱附及扩散性能

用智能重量分析仪(IGA-100)在较高温度下测定了5A分子筛(自制)对正庚烷吸附/脱附等温线及其滞后环;计算TIE庚烷在5A分子筛上的吸附热和吸附、脱附扩散系数,分析了正庚烷在5A分子筛微孔内吸附作用.结果表明:吸附温度升高,正庚烷吸附等温线优惠程度明显降低,有吸附滞后环;在523 K下,5A对正庚烷的平衡吸附量为0...     

空气在二甲基硅油和液压油中扩散系数的测量

A piston-cylinder apparatus was established to measure the solubility and diffusivity of air in dimethyl silicone oils and in hydraulic oils based on the PVT state equation of air and the solution of unsteady one-dimensional diffusion equation. The measured diffusivity-temperature relation can be well fitted by the Arrhenius equation for engineering applications. The correlation between the solute diffusivity D and solvent viscosity  is examined. In terms of Eyring’s activation theory, the activation in the air-silicone-oil diffusion process is quite different from that in the momentum transport of the silicone oil: the activation entropy of the former is positive while that of latter is negative. However, the activation enthalpies of the two processes are in the same order of magnitude, which leads to the observation that D/T is roughly constant.     

碳酸二乙酯联产碳酸甲乙酯技术开发及产业化

阐述了碳酸二乙酯联产碳藏甲乙酯的工艺路线和开发过程，预测市场情况。     

碳酸二乙酯黏度和密度的实验测量及数据关联

采用振动弦黏度/密度计对碳酸二乙酯的黏度与密度进行了实验研究,测量的温度范围为263～363 K,压力范围为0.1～20 MPa。实验系统黏度和密度测量的不确定度分别为±2.0%和±0.2%。利用得到的实验数据,分别拟合了碳酸二乙酯黏度和密度方程。黏度实验数据与方程的平均绝对偏差为0.54%,最大绝对偏差为1.98%;密度实验数据与方程的平均绝对偏差为0.042%,最大绝对偏差为0.12%。最后将实验数据与文献数据进行了比较。为碳酸二乙酯作为替代燃料等研究提供了基础数据。     

常压气相羰基化合成碳酸二乙酯

用积分反应器在固定床连续流动反应体系中进行CO气相催化合成碳酸二乙酯。研究了以各种活性炭为载体的钯催化剂、催化剂浸渍方法和不同催化剂组成对合成碳酸二乙酯催化活性和选择性的影响 ,得到了有发展前景的催化剂。结果表明 ,以逐滴浸渍法 ,使用M3 为助催化剂 ,反应温度 1 0 5～ 1 2 0℃时 ,催化剂有较好的活性和选择性。     

On the use of internal mass transfer coefficients in modeling of diffusion and reaction in catalytic monoliths

We utilize the recently developed concept of internal or intraphase mass transfer coefficient to simplify the problem of diffusion and reaction in more than one spatial dimension for a washcoated monolith of arbitrary shape. We determine the dependence of the dimensionless internal mass transfer coefficient (Sh_i) on washcoat and channel geometric shapes, reaction kinetics, catalyst loading and activity profile. It is also reasoned that the concept of intraphase transfer coefficient is more useful and fundamental than the classical effectiveness factor concept. The intraphase transfer coefficient can be combined with the traditional external mass transfer coefficient (Sh_e) to obtain an overall mass transfer coefficient (Sh_app) which is an experimentally measurable quantity depending on various geometric and transport properties as well as kinetics. We present examples demonstrating the use of Sh_app in obtaining accurate macro-scale low-dimensional models of catalytic reactors by solving the full 3-D convection-diffusion-reaction problem for a washcoated monolith and comparing the solution with that of the simplified model using the internal mass transfer coefficient concept.     

碳酸二乙酯与苯酚选择性合成苯乙醚的研究

研究了以分子筛NaY为载体,以乙酸钾为活性组分的固体碱催化剂对苯酚与碳酸二乙酯气固相催化合成苯乙醚的过程,采用CO_2-TPD和N_2吸附脱附的方法对催化剂进行了表征,考察了乙酸钾负载量对催化剂活性的影响以及反应条件对该反应的影响.结果表明随乙酸钾负载量的增加催化剂的碱性先增加后减小,这主要是由于过高的负载量会堵塞催化剂内孔,从而抑制其碱性中心发挥作用.乙酸钾负载量为15%质量分数的催化剂对该反应有最好的催化性能.当反应温度为593 K,空速为1.5 h~(-1),碳酸二乙酯和苯酚摩尔比为1.2时,苯酚的转化率和苯乙醚的选择性都可以达到100%.     

葡萄糖水溶液扩散系数的测定与关联

液相扩散系数在化工数据中起着非常重要的作用,由于液体结构及扩散本身的复杂性,至今还没有一个合理的理论模型来预测液相扩散系数,有必要从实验和理论上对不同的体系进行研究.制备了金属膜池,用氯化钾溶液标定了膜池常数,并用已有可靠文献值的蔗糖水溶液验证了装置的可靠性.测定了298.15～328.15 K不同温度下葡萄糖水溶液的积分扩散系数,考察了温度对扩散系数的影响.在实验数据的基础上,提出一个有温度关联项的半经验模型,关联和计算了本实验的数据,结果与实验值吻合很好.     

碳酸二甲酯和乙醇酯交换合成碳酸二乙酯工艺研究

碳酸二乙酯分子结构中含有活性基团乙氧基和羰基,化学性质活泼,是一种重要的有机合成中间体、溶剂和性能优良的燃料添加剂,在化工领域具有很高的应用价值。以碳酸二甲酯和乙醇为原料,甲醇钠为催化剂,通过酯交换反应合成碳酸二乙酯。气相色谱分析表明,在酯与醇物质的量比1∶20、催化剂用量为碳酸二甲酯质量的1.0%、反应温度78 ℃和反应时间1 h条件下,碳酸二甲酯转化率达99%,碳酸二乙酯和碳酸甲乙酯选择性分别为86%和14%。     

Synthesis of diethyl carbonate from ethanol through different routes: A thermodynamic and comparative analysis

In this study, thermodynamic analysis of various possible synthesis routes of diethyl carbonates (DEC), a benign organic carbonate, was carried out and a comparative analysis was performed. Chemical equilibrium constants at standard conditions were calculated using Gibbs free energy of the system. The Benson group contribution method was used to estimate standard heat of formation and standard entropy change of some raw materials/components like dimethyl carbonate. Variation of heat capacity (C_p) with temperature was estimated for different components from the Rozicka‐Domalski model. Variation of chemical equilibrium constants with temperature and pressure was studied for various routes. Synthesis of DEC from ethylene carbonate (EC) was also found to be better considering equilibrium constants at room temperature. The CO₂ route was found to be the most unfavourable route for DEC synthesis due to stability of CO₂ molecules. Moreover, DEC synthesis through the urea route was found to be best at high temperatures since the equilibrium constants were found to increase exponentially. Experiments were conducted for DEC synthesis using the EC route at two temperatures. Activity coefficients were calculated using the UNIFAC model. Experimentally and theoretically determined chemical equilibrium constant values were found to be similar. PRO/II was also used to minimize Gibbs free energy of the system and estimate the equilibrium constants and the results were comparable with those obtained by the equilibrium constant method and the trend was found to be the same for both the methods.     

乙酸乙酯-碳酸二乙酯二元体系平衡数据的测定及模拟

采用改进型ROSE汽液平衡釜在100.47 kPa下测定乙酸乙酯(EA)-碳酸二乙酯(DEC)二元体系的汽液平衡数据,进一步得到的液相活度系数,经面积积分法检验符合热力学一致性。并借助化工过程模拟软件,同时采用NRTL和Wilson方程对实验数据进行关联得到模型参数,回归出不同模型下汽相组成与实验中的数据进行比较,平均偏差分别为0.007 8和0.006 8,结果表明2种模型都符合需要。研究结果将为有关工程设计提供化工数据。