添加晶种的KNO_3水溶液间歇结晶动力学模型

针对添加晶种的二次成核结晶过程的特点,并基于Beer Lambert定律、ΔL定律和粒数衡算理论,建立了包含透光率变量的间歇结晶动力学模型。运用该模型对KNO3水溶液冷却结晶实验的溶液质量分数、相对过饱和度以及透光率数据进行关联,一次性获得了结晶体系的二次成核和生长动力学参数,其值与文献值吻合较好。尝试以光学法关联动力学模型的研究,将有助于结晶机理的深入认识,为动力学模型的进一步发展提供思路。     

KNO3-H2O溶液间歇结晶动力学

基于ΔL定律推导了晶体线性生长速率的数学表达式，利用已建立的溶液间歇结晶动力学实验研究手段实现了溶液透光率和浓度的在线测量.利用经验模型关联线性生长速率和相对过饱和度求取了生长动力学参数，并与文献值进行了比较.结果发现：对于自发成核结晶过程，综合动态透光率、过饱和度和经验模型可对成核和生长阶段进行定性识别.     

KNO3-H2O溶液间歇结晶动力学

基于ΔL定律推导了晶体线性生长速率的数学表达式,利用已建立的溶液间歇结晶动力学实验研究手段实现了溶液透光率和浓度的在线测量.利用经验模型关联线性生长速率和相对过饱和度求取了生长动力学参数,并与文献值进行了比较.结果发现：对于自发成核结晶过程,综合动态透光率、过饱和度和经验模型可对成核和生长阶段进行定性识别.     

流化床中磷酸二氢钾结晶成核动力学研究

运用连续流化床结晶装置,参照工业装置结晶条件,研究了磷酸二氢钾在25℃条件下的结晶成核动力学规律。采用流化床结晶过程的成核动力学模型,利用多元线性回归得到成核动力学参数,并通过实验验证动力学参数的可靠性。结果表明,磷酸二氢钾结晶二次成核中流体剪切成核占主导地位,即B0=1.02×10-4M0.T563R1e.654,实验测试过程中晶体聚结和宏观破碎的影响可以忽略。     

流化床中磷酸二氢钾结晶动力学研究

对磷酸二氢钾在流化床结晶器中的结晶动力学进行了实验探讨。研究了磷酸二氢钾在25℃下的结晶过程及过饱和度,循环流量和悬浮密度对其成核、生长速率的影响。初步建立动力学模型,利用多元非线性回归方法拟合了晶体成核、生长动力学方程。研究发现磷酸二氢钾在流化结晶器结晶过程中过饱度占成核、生长主导地位,说明动力学参数模型是基本可靠的。这对工业结晶生产、应用流化床结晶器的模拟放大具有重大的实际指导应用意义和对生产优质的磷酸二氢钾晶体具有一定的参考意义。     

普鲁卡因青霉素的生成反应动力学

实验采用激光测量装置,测定了在不同温度及反应浓度下,普鲁卡因青霉素反应结晶过程的反应及成核时间,通过最优化方法模拟得到反应动力学参数,建立了合理的普鲁卡因青霉素反应结晶过程的反应动力学模型。     

氯氧化铋反应结晶动力学研究

在铋盐水解制备氯氧化铋的反应结晶过程中,控制氯氧化铋晶体成核和生长速率可影响氯氧化铋晶体的形貌、粒径和分散性。为此,选用间歇动态法研究了氯氧化铋晶体成核与生长动力学,采用矩量变换法建立了结晶过程动力学模型,并用最小二乘法对实验数据进行多元线性回归,获取了动力学模型参数。研究结果表明：当氯氧化铋晶体粒度≥3 μm时,其晶体生长速率符合粒度无关生长模型;晶浆悬浮密度和过饱和度对成核速率均有显著影响;溶液过饱和度对成核速率的影响较生长速率的影响更为显著。     

阿莫西林成核与生长动力学

阿莫西林现有结晶工艺获得的晶体粒度过小,直接影响到后续的过滤、干燥以及包装运输,研究其结晶动力学参数以指导结晶工艺,控制结晶过程中晶体的成核速度与生长速度,对提高晶体粒度有着重要意义。文章分别采用激光法和显微摄像的方法对阿莫西林结晶过程中初级成核、二次成核和单晶体生长速度进行了测定,计算出动力学相关数据。通过实验确定阿莫西林初级成核中均相成核与非均相成核的分界过饱和度S=4.5以及各自对应的成核自由能与成核半径,确定了二次成核发生时间与过饱和度间的关系以及阿莫西林晶体的生长速率与过饱和度的关系,并由生长指数m=1.995 5推出阿莫西林的生长机制为螺旋错位生长。通过阿莫西林结晶动力学研究为改进和优化结晶过程提供了理论基础。     

蛋氨酸CO2酸化半间歇反应结晶动力学研究

针对海因法合成蛋氨酸工艺，利用间歇动态法、以蛋氨酸钾为原料研究了CO₂酸化条件下蛋氨酸的反应结晶过程，建立结晶动力学模型。通过矩量变化法求解粒数衡算方程，利用最小二乘法对数据多元线性回归得到结晶动力学参数。结果表明：晶体生长类型为粒度无关生长，晶体生长活化能为21.01 kJ·mol^-1,成核与生长速率方程中过饱和度的指数分别为0.62和1.52,晶体聚结对结晶过程的影响不可忽略。气体表观速率、搅拌速率对晶体成核与聚结均有明显影响。高过饱和度与高搅拌转速不利于晶体平均粒径的增加。     

溶液结晶动力学研究进展

结晶动力学的研究一直是结晶过程中的热门话题。通过结晶动力学的研究可以模拟、改进和优化结晶过程,也可以用于结晶器的设计和放大。综述了采用晶体悬浮法研究结晶动力学的进展,其中主要包括成核、晶体生长、聚积和破碎动力学模型的计算。     

溶液自发结晶过程动力学参数研究

The batch cooling crystallization initiated from spontaneous nucleation for aqueous solution of potas- sium nitrate was studied.The concentration and transmittance data were acquired on line throughout the operation. Based on solute mass transfer in both liquid and solid phases,a kinetic model was deduced by assuming that the late period of primary nucleation resembles the initial period of the secondary nucleation.Nucleation and crystal growth stages were identified.Kinetic parameters were estimated piecewise from online experimental data and compared with those in literature.The estimated kinetic parameters for stages without apparent primary nucleation agreed well with those in literature.Further,a simulated concentration curve was also drawn from the estimated kinetic parameters and it matched well with that in experiment.     

Quantitative design of seed load for solution cooling crystallization based on kinetic analysis

Seed load of crystallization has a direct effect on the product qualities. To further reveal the effects of seed load on crystallization kinetics and improve the product size distribution, the aqueous solution of potassium nitrate (KNO₃–H₂O) is employed as a model system and the relevant kinetic experiments are conducted in a batch cooling crystallizer. The crystal nucleation and growth rate parameters are firstly estimated with the concentration and transmittance data using a mathematical model reported in our lab, and then the backward calculations with the help of the model parameters are successfully performed. It is found that the nucleation capacity decreases and growth capacity increases with increasing seed load, and the size distribution of crystal products tends to be more uniform. However, with the increasing of seed load, the linear growth rate of single crystal and the mean size of products both reduce accordingly. Based on the calculational and experimental results, a quantitative design scheme concerning seed load is proposed by further kinetic analyses, and the corresponding verification experiments are carried out. The results show that under the guidance of the proposed scheme, the size distribution of crystal products is more concentrated and the mean size of final particles can also escape from reducing obviously.     

Cure properties of methacrylate‐type prepolymer that include cyclohexane moiety

New methacrylate‐type prepolymers including a cyclohexane moiety, which may be used as binder resins for the color filter resist of liquid crystal display, were synthesized by the reaction with methacrylic acid (MA) and epoxy resins. Their photo‐ and thermal cure properties were investigated using Fourier transform infrared spectroscopy and DSC, respectively. Their photocure reaction rates and the extent of reaction conversion increased with the concentration of photoinitiator and intensity of UV irradiation. An increase of photocure reaction temperature was attributed to the increase of photocure reaction rate and the degree of reaction conversion for EHPE‐3150‐MA prepolymer. Thermal stability was studied by observing changes in the transmittance of the photocured polymer film upon heating. The polymer was extremely stable, showing almost no transmittance change in the visible range even after being heated at 250°C for 1 h. We also investigated thermal cure reaction using a DSC technique. An autocatalytic kinetic reaction occurs in these systems, and the kinetic parameters of all systems were reported in terms of a generalized kinetic equation that considered the diffusion term. It can be shown that the reaction conversion rate of NC‐9110‐MA is faster than that of EHPE‐3150‐MA, regardless of the kind of thermal initiator. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 43–52, 2004     

Dynamics and control of aggregate thin film surface morphology for improved light trapping: Implementation on a large-lattice kinetic Monte Carlo model

This work demonstrates the use of feedback control, coupled with a suitable actuator design, in manufacturing thin films whose surface morphology is characterized by a desired visible light reflectance/transmittance level. The problem is particularly important in the context of thin film manufacturing for thin film solar cells where it is desirable to produce thin films with precisely tailored light trapping characteristics. Initially, a thin film deposition process involving atom adsorption and surface migration is considered and is modeled using a large-lattice (lattice size=40,000) kinetic Monte Carlo simulation. Subsequently, thin film surface morphology characteristics like roughness and slope are computed with respect to different characteristic length scales ranging from atomic to the ones corresponding to visible light wavelength and it is found that a patterned actuator design is needed to induce thin film surface roughness and slope at visible light wavelength spatial scales, which lead to desired thin film reflectance and transmittance levels. Then, an Edwards–Wilkinson-type equation (a second-order stochastic partial differential equation) is used to model the surface evolution at the visible light wavelength spatial scale and form the basis for the design of a feedback controller whose objective is to manipulate the deposition rate across the spatial domain of the process. The model parameters of the Edwards–Wilkinson equation are estimated from kinetic Monte Carlo simulations and their dependence on the deposition rate is used in the formulation of the predictive controller to predict the influence of the control action on the surface roughness and slope throughout the thin film growth process. Analytical solutions of the expected surface roughness and surface slope at the visible light wavelength spatial scale are obtained by solving the Edwards–Wilkinson equation and are used in the control action calculation. The cost function of the controller involves penalties on both surface roughness and slope from set-point values as well as constraints on the magnitude and rate of change of the control action. The controller is applied to the large-lattice kinetic Monte Carlo simulation. Simulation results demonstrate that the proposed controller and patterned actuator design successfully regulate aggregate surface roughness and slope to set-point values at the end of the deposition that yield desired levels of thin film reflectance and transmittance.     

灵活多效催化裂化工艺集总动力学模型

针对灵活多效催化裂化(FDFCC)工艺,以工业装置数据为基础建立了重油提升管催化裂化10集总和汽油提升管催化裂化7集总动力学模型,求取了10集总模型的43个动力学参数和7集总模型的18个动力学参数.结果表明,所获得的模型动力学参数是可靠的,所建立的模型能够较好地预测FDFCC装置的产品产率,并对汽油组成和丙烯产率具有良好的预测性.     

明胶层中的扩散和反应的动力学研究 (Ⅱ)扩散伴随二级反应的动力学模型

设计一个数值模型用来描述反应物在明胶层中边扩散边与另一种反应物发生二级反应的动力学过程。这个模型与相应的动力学实验相结合可以测出反应物在明胶层中的扩散系数和反应速率常数。在动力学参数齐备的情况下,可以预测动力学过程,并且提供反应物和产物在明胶层中不同时间的空间分布等各种重要的中间过程的描述。模型为研究明胶层中的反应动力学过程提供了有效的分析工具。     

5429双马来酰亚胺树脂的固化动力学研究

通过差示扫描量热法(DSC)研究了5429双马树脂的固化过程。分别使用Kissinger模型和Flynn-Wall-Ozawa模型计算得到了5429双马树脂动力学参数。结果表明Kissinger模型与FWO模型计算得到的动力学参数较为接近,验证了两个动力学模型的有效性。由于5429双马树脂的固化反应为一级反应,因此代入相应的固化动力学参数可得到其固化动力学方程。此外,通过T-β外推法可计算得到5429双马树脂凝胶化温度、固化温度和后处理温度等特征温度。     

八甲基环四硅氧烷与氨取代基有机硅单体的共聚动力学Ⅱ模型考核与结果讨论

对前文 (I)的共聚动力学模型进行了分析与简化 ,并分别通过对各影响因素的单因素实验和多因素相互作用实验对模型进行了进一步的考核 ,确定了模型参数并通过模型对聚合动力学行为作了说明