在流化床中溶液的蒸发与干燥成粒

在目前化学工业中从溶液得到干燥的颗粒成品,需要经过蒸发、结晶、干燥与造粒等工序,不但操作繁复,还需耗用大量金属材料与基建费用。而应用流态化的方法有可能使蒸发、干燥与成粒等工序在一起进行,如苏联的罗曼柯夫(П.Т.Романков)等曾在流化床中研究了水分高达50～80%的染料等悬浮浆状物料的干燥;捷克的麦克凡尔特(M.Markvart)也曾对氯化钠、氯化钙、硝酸钙、硫酸钠等无机盐溶液进行了干燥实验,并得到了颗粒状的成品。他们一致指出,由于在流化床中气流的剧烈搅动与良好的传热,因此可以对一些性质此较稳定的溶液直接进行干燥,同时此种技术也是一种理想的造粒技术。     

锥形流态化床干燥无机盐溶液的研究

本文叙述了应用锥形流态化床进行溶液干燥。锥形容器系用铝板制成,锥形角为28°,锥形部分最小直径为φ33毫米。干燥后物料含水量与转筒干燥法相近似,而其干燥强度为转筒法的13倍,空气消耗量减少76千克/千克水。本法工艺过程简单、操作简便、节约能量、降低基建投资,有显著的经济效益和良好的社会效益。     

开路循环热泵用于高浓度无机盐溶液蒸发过程的研究

近十几年,由于能源危机的影响,国外对热泵的研究工作逐渐重视起来,並应用到能耗较大的干燥、精馏、蒸发工艺过程中。热泵是热机的逆过程。热机将热能转换为机械能,而热泵是将机械能转换为热能。人们所熟悉的冷冻机装置(图1),传热工质转换成机械功W,在热端冷凝器工质传给     

无机盐对SDS溶液表面张力的影响

通过最大气泡法表面张力的测定,研究了无机盐NaCk、CuCl2、ZnSO4、AICI,和Al2(SO4)3等对十二烷基硫酸钠(SDS)溶液表面张力的影响.结果表明:在一定浓度范围内,随着无机盐浓度的增大,SDS溶液的表面张力逐渐减小;相同浓度的不同无机盐,价态越高,对SDS溶液表面张力降低越明显,3种无机盐对SDS溶液表面张力影响程度依次为:NaCl＜ZnSO4＜Al2(SO4)3.     

无机盐溶液纳滤膜技术的研究进展

无机盐溶液的纳滤膜分离技术已成为研究纳滤分离过程的一个重要方面。介绍了目前用于解释无机盐溶液纳滤膜分离机理的几种模型（电荷模型以及静电位阻模型）和种类，综述了无机盐纳滤分离性能研究概况，分析了无机盐种类及其浓度、纳滤膜荷电性、操作条件等对单组分无机盐溶液纳滤分离性能的影响，并对其作用机理进行了探讨。同时简要分析了纳滤膜在混合无机盐溶液体系中的影响因素，并对该法的发展前景进行了展望。     

用蒸发法干燥溶剂

本文讨论了最近在国外提出的溶剂脱水干燥技术——蒸发法的理论问题,并首次采用间断蒸发法对四氯化碳、氯苯等溶剂进行试验和生产应用取得较好的脱水效果,所得数据并与理论计算值进行了比较。     

硫酸铝溶液蒸发设备设计探讨

本文以硫酸铝溶液的腐蚀本质出发进行合理选材,提出在目前条件下,钛材作为硫酸铝溶液蒸发设备是比较合适的。探讨了提高钛设备耐蚀性能的途径,设计了结构合理、传热效率高的新型蒸发换热器,大大提高了生产能力,取得了显著的经济效益。     

氯化钙溶液蒸发工艺对比

在环氧氯丙烷生产过程中,产生大量氯化钙废水,将该氯化钙废水处理并浓缩后制成氯化钙产品外售.比较了将氯化钙溶液浓缩至35％(质量分数)的三效顺流和三效逆流蒸发工艺,顺流蒸发工艺蒸汽消耗略高,但减少了泵的使用,降低了电耗,且循环水用量低,因此,顺流蒸发工艺更合适.     

干燥与蒸发设备的发展趋势

<正> 结构简单、可靠性高,减少维修、提高热效,这是当今干燥和蒸发设备的发展趋势。为使操作成本降低,设计制造者在考虑如何从系统中回收更多的热量以及将干燥蒸发操作与其它的单元操作如反应,凝聚,粉碎、混合和(或)分离等结合起来。 为此,可将干燥和蒸发设备分成二大类,一是产品型,二是机械功能型。这个观点将在设备的发展和改革中起到重要的指导作用。     

Evaporation Kinetics of Single Droplets Containing Dissolved Bioaiass

Luikov approach was applied to predict drying time and temperature of a droplet containing liquid substrate of entobacterin in the falling drying rate period. Analytical expressions describing both average and local temperatures of the particle in the drying process were derived and solved. Constants necessary to solve the equations, describing certain material properties and material moisture bonding were found in simple experiments. An experimental relationship of Rebinder number and moisture content of the material enabled to calculate changes of average droplet temperature in the falling drying rate period. Analytical solutions of heat transfer equations for shrinkage core model both for a linear and exponential change of moisture content of the droplet in the drying process were delivered. Employing experimental heat transfer coefficient, drying time and droplct temperature field were determined. Comparison of experimental and predicted drying times as well as droplet temperatures shows small discrepancy. Results obtained can be used to predict quality of labile products in the course of drying.     

Evaporation Kinetics of Single Droplets Containing Dissolved Bioaiass

ABSTRACT

Luikov approach was applied to predict drying time and temperature of a droplet containing liquid substrate of entobacterin in the falling drying rate period. Analytical expressions describing both average and local temperatures of the particle in the drying process were derived and solved. Constants necessary to solve the equations, describing certain material properties and material moisture bonding were found in simple experiments. An experimental relationship of Rebinder number and moisture content of the material enabled to calculate changes of average droplet temperature in the falling drying rate period. Analytical solutions of heat transfer equations for shrinkage core model both for a linear and exponential change of moisture content of the droplet in the drying process were delivered. Employing experimental heat transfer coefficient, drying time and droplct temperature field were determined. Comparison of experimental and predicted drying times as well as droplet temperatures shows small discrepancy. Results obtained can be used to predict quality of labile products in the course of drying.     

Theoretical Drying Model of Single Droplets Containing Insoluble or Dissolved Solids

A literature survey of published single-droplet drying models has exposed their various shortcomings. An advanced theoretical model of drying of single droplets, containing either insoluble or dissolved solids, has been developed and numerically solved. The validation of the developed model has been accomplished by comparison of the predicted temperature and mass histories with published experimental data for slurries of silica and skim milk solution under different conditions. The results of simulations showed a good agreement between the calculated curves and experimental points in all case studies.     

Evaporation of Multicomponent Droplets

ABSTRACT

The evaporation of multicomponent drops having diameters on the order 10 /am was investigated using electrodynamic levitation and light-scattering measurements. Multicomponent drops representative of diesel fuels and binary drops were studied. The binary system consisted of the halogenated compounds 1-iododocane and 1-bromotetradecane, and the model fuel drops were composed of hexadecane, 1-methyl naphthalene, and cis- and trans-decahydronaphthalene (decalin). The effect of an additive, tertiary butyl peroxide, on the evaporation of the multicomponent system was explored, and some data are reported for the additive ethyl hexyl nitrate. The additives were found to have negligible effect on the evaporation rate. The measured evaporation rates are compared with a theoretical analysis based upon diffusion-controlled evaporation using the UNIFAC (Reid et al., 1987) model for liquid phase activity coefficients. The model was found to be in good agreement with experiment.     

若干无机盐对聚丙烯酰胺溶液粘度的影响

探讨了无机盐溶液中阴阳离子对聚丙烯酰胺(PAM)溶液粘度的影响,确定了影响PAM溶液粘度的主要因素是二价阳离子(如ca2 及Mg2 离子)。     

Transparency of Hydrophobic Vinyl Polymers Containing Small Amounts of Inorganic Chloride Salts

Termination of n-BuLi-initiated anionic polymerizations of vinyl monomers (i.e. styrene or butadiene) by chlorotrimethylsilae (CTMS) or methoxytrimethylsilane (MTMS) resulted in an opaque or transparent polymer product. Small amounts of salt (i.e. LiCl from CTMS- or Li(OCH₃) from MTMS-terminated polymerization) generated during termination stage was presumably the cause of the transparency difference. To verify this, turbid solutions were prepared by mixing transparent polymers (prepared from a H₂O-terminated anionic polymerization) with controlled amounts of LiCl in mixed tetrahydrofuran/cyclohexane (THF/CHE) solvents. Reduced viscosity (_red) and particle size (determined from light scattering) of these turbid solutions were found to increase with polymer and LiCl content. On the contrary, both _red and particle size decrease with increasing THF content of the mixed solvent. These results suggest that interactions between the LiCl/THF complex and the polymer chains are responsible for particle formation and hence turbid appearance of the solutions. Solution ⁷Li NMR spectra of the salt/polymer solutions indicated that polystyrene (PSt) has stronger interactions with LiCl as compared to polybutadiene (PBu), which resulted in a more homogeneously salt distribution in PSt than PBu as evaluated from the TEM micrographs of the corresponding bulk samples after solvent removal. A model with the included LiCl/THF complexes surrounded by the polymer coils was proposed to account for the resulting turbidity in solutions and in the bulk state.     

固着纯组分液滴蒸发的研究综述

本文对固着纯组分液滴的蒸发研究现状进行了综合评述。介绍了固着液滴蒸发的恒接触半径模式、恒接触角模式及混合模式,分析了完全润湿和部分润湿两种固着液滴的蒸发过程及其特点,系统讨论固着液滴的蒸发动力学理论规律,并对固着液滴蒸发的实验研究进行了简要介绍。     

微胶囊对无机盐的改性研究

利用物理化学原理进行相分离,利用壁材凝聚包覆的物理化学方法,对硝酸铵进行包覆,使硝酸铵的吸湿性和结块性得到改善;对产物进行分析,得到产物与硝酸铵的性质对比数据;并讨论了影响产物质量的因素。实验结果表明：利用微胶囊技术对硝酸铵进行改性,在一定条件下是可行的,并达到了缓释的目的。     

Quaternary Onium Salts Immobilized on Inorganic Matrices

Onium salts immobilized on silica gel and alumina show unusual properties because of the presence of the polar inorganic support. Under liquid—liquid phase-transfer catalysis conditions these systems can also catalyze reactions carried out without stirring, and unlike the corresponding onium salts supported on polystyrenic matrix, they do not need the use of polar solvent. Moreover, different matrices with different geometries in the micropores are differently functionalized and may induce selectivity towards reagents with different molecular size. The polar and hydrophilic matrix strongly affects the affinities of the immobilized onium salts in the anion exchange process, producing a higher affinity towards hydrophilic inorganic and lipophilic organic anions, with respect to that observed for the homogeneous and polystyrene supported onium salts. In aqueous solution the onium salts supported on inorganic matrices are able to adsorb the reactants and to vary the reaction microenvironment as the micellar catalysts do.     

Evaporation and Condensational Growth of Liquid Droplets in Nonisothermal Gas Mixtures

A theoretical study and coupled analytical model of the growth rates of a droplet in a nonisothermal gas mixture are presented. The derived model explicitly accounts for the influence of the properties of the gaseous media on the transport processes in an aerodisperse system. The Stefan flux as well as temperature and composition dependencies of the transport coefficients are accounted for simultaneously, still resulting in a convenient analytical expression. Such an expression is especially useful to use in a numerical GDE solution routine, in which much time cannot be spent in the individual physical processes. The results of previous studies are compared to our model predictions. Numerical calculations are performed for a wide range of saturation ratios for the water droplet-humid air system and compared with experimental data. The presented new model is an improvement on the existing ones, especially in cases in which the mass transfer rates are large, resulting in a nonuniform temperature field.