最新的搅拌混合技术

着重介绍了国外搅拌混合技术的最新发展动态,从搅拌流动的流动特性角度,将新型搅拌机分为三类,分别为抽气罩壳型（宏观循环流）;定子与转子啮合型（局部高剪切流）;组合型（宏观循环加局部高剪切）。指出新型搅拌机可实现反应,分散,破碎,均一及乳化等多种过程,正向着多功能,多用途的方向发展。     

陶瓷原料搅拌混合技术

本文论述了搅拌机设计的基本原理,详细分析了搅拌混合过程中各项参数的控制。     

RIM混合室中对撞射流混合性能研究

以偶合反应的选择性,评价射流对撞混合器混合性能。研究了低粘流体低速条件下,结构参数(H/d、d/D)和流动参数(动量比)γ,Re)对混合质量的影响。认为 H/d 是非敏感参数,d/D 减小有利于混合,而动量比偏离l对混合稍不利,不能仅用雷诺数作为设计放大的准则。     

搅拌槽混沌混合研究进展

介绍了层流状态下搅拌槽内普遍存在的混合隔离区,它的存在成为混合的一大障碍,而混沌混合的提出和应用极大地提高了混合效率.阐述了混沌混合的基本原理是通过动力学扰动的方式破坏流体颗粒运动轨迹的周期性.同时介绍了截止到目前关于搅拌槽内混沌混合的方法,主要有变速搅拌、偏心搅拌、往复搅拌等,对这些方法的数值模拟和实验研究结果都证明,混沌混合能很好地改善搅拌槽的混合效果,与传统的稳态搅拌方式相比,混沌混合具有很大的优越性.     

浸没循环撞击流反应器中的微观混合

Micromixing in the submerged circulative impinging stream reactor (SCISR) developed by the authors is investigated with the Bourne's reaction scheme. The values measured for the impinging velocity, u0, under the conditions of SCISR normal operation, only is of the order of 0.1m·s-1, are much slower than that inferred, suggesting low power requirement for operation. The values of the characteristic time constant for micromixing, tM, determined in the impinging velocity range of 0.184m·s-1 相似文献   

搅拌槽内非牛顿流体的微观混合特性

在直径为0·476m的搅拌槽内,分别选用三窄叶翼型搅拌桨和标准六直叶涡轮搅拌桨,采用羟乙基纤维素(HEC)水溶液非牛顿流体作为工作体系,以改进的硫酸铜沉降反应与氯乙酸乙酯水解反应的平行竞争反应作为研究微观混合的反应工作体系,在质量分数为0·1%~0·5%的HEC水溶液中,排除硫酸铜副反应的影响,利用铜离子质量浓度与可见光吸光度的线性关系,考察了进料时间、搅拌转速、溶液黏度、流体的非牛顿性以及搅拌桨类型等因素对副产物收率(XQ)的影响规律。结果表明,当进料时间超过临界进料时间3500s后,X_Q不再改变;随着搅拌转速的增加,X_Q减小,但其减小的趋势逐渐变缓;在相同转速下,X_Q随着流体黏度的增加而增加,但增加的趋势有所减缓;对于黏性流体不能仅仅采用雷诺数作为放大准则;在相同的能量耗散速率及桨叶区进料的情况下,Damkohler准数较大的标准六直叶涡轮搅拌桨的X_Q较小。     

介质循环搅拌容器应用前景的分析

文章详细介绍了一种新型设备－介质循环搅拌容器，并详细对比了传统的机械搅拌容器的优缺点。     

动物细胞发酵缶的混合与剪切性能评价

微载体悬浮培养动物细胞条件下,发酵缶的混合与剪切性能优劣对动物细胞的培养效果至关重要。本文研究了NBS动物细胞发酵缶的流体混合时间、搅拌功率和时均速度分布,探讨了微载体及动物细胞所受到的流体作用力的计算方法,为设计大规模动物细胞发酵缶不变提供了部分依据。     

循环剪切法制脂工艺的应用及效果

本文简要介绍了采用循环剪切法制脂工艺的新老工艺对比、产品质量对比及其应用效果。     

搅拌生物反应器的循环时间分布和混合结构模型

利用磁粒子流动跟踪法对搅拌生物反应器的循环时间分布进行测定,并将Rushton径向流桨和两种新型轴向流桨在不同介质粘度和转速下的循环时间分布进行比较和性能评价。建立了单桨搅拌生物反应器的混合结构模型,对循环时间分布数据进行拟合,求得模型参数,进而讨论了不同实验条件下模型参数的变化。结果表明,对于非牛顿、高粘度发酵过程,轴向流桨比Rushton桨具有更好的混合特性。     

发酵罐中剪切环境与菌体形态和代谢

结合青霉素发酵过程,考察了产黄青霉形态与剪切环境的关系;在搅拌槽内流场研究的基础上,分析了现有各种表征发酵罐内总体剪切环境的参数的合理性,提出了菌体对高强度剪切呈现出“印象衰减”效应这一新观点.据此而得的特征剪切强度,可用于发酵罐中轴向、径向叶轮组合搅拌的设计.     

SOLIDS CIRCULATION IN SPOUTED AND SPOUT-FLUID BEDS WITH DRAFT-TUBES

A 20 cm semi-cylindrical spout-fluid bed with a draft-tube has been used to investigate the effect of various physical parameters on the solids circulation rate, A new method has been developed by which these data can be easily and accurately collected. Equations are presented which can be used to predict the maximum attainable solids circulation rate and the spouting velocity required to achieve this maximum for the unit operating in spouting mode. The circulation trends are shown to be a direct result of the phenomena of entrainment and jetting occurring in the entrainment zone investigated visually with a video camera. Preliminary gas bypassing experiments were also performed which show the ability to almost eliminate spout gas bypassing to the annulus with appropriate auxiliary gas addition.     

CIRCULATION OF GAS AND LIQUID PHASES IN EXTERNAL-LOOP AIRLIFT REACTORS

The effects of the horizontal connection length (0.3 ≤ L_c ≤ 0.6 mrpar;, the cross-sectional area ratio of downcomer-lo-riser (0.28≤A_d/A_r≤0.53rpar;, and the superficial gas velocity on the circulation gas flow rate were studied. The circulation liquid velocity, the downcomer gas holdup, and the bubble size in the downcomer were also investigated. In order to measure the circulation gas flow rate, a gas-liquid separator was installed at the bottom connection between riser and downcomer. Both of the circulation gas flow rale and the circulation liquid velocity strongly depended on the superficial gas velocity as well as the cross-sectional area ratio of downcomer-to-riser and the horizontal connection length. An useful correlation for the circulation gas flow rate was obtained in terms of the superficial gas velocity, the cross-sectional area ratio of downcomer-to-riser and the horizontal connection length.     

LIQUID CIRCULATION PATTERNS AND THEIR EFFECT ON GAS HOLD-UP AND AXIAL MIXING IN BUBBLE COLUMNS

Liquid velocity profiles in a bubble column were measured with the aid of a hot-film anemometer. Two different types of profiles were detected that were characterized by the formation of a boundary layer at the column wall. Under slow flow conditions, the boundary layer is large and controls the liquid velocity profile, but in turbulent flow the boundary layer is very small and has no significant effect on the velocity profile. Microscopic and macroscopic balances were used to predict both the liquid velocity profile and the average liquid velocity.

The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended.     

LIQUID CIRCULATION PATTERNS AND THEIR EFFECT ON GAS HOLD-UP AND AXIAL MIXING IN BUBBLE COLUMNS

Liquid velocity profiles in a bubble column were measured with the aid of a hot-film anemometer. Two different types of profiles were detected that were characterized by the formation of a boundary layer at the column wall. Under slow flow conditions, the boundary layer is large and controls the liquid velocity profile, but in turbulent flow the boundary layer is very small and has no significant effect on the velocity profile. Microscopic and macroscopic balances were used to predict both the liquid velocity profile and the average liquid velocity.

The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended.     

自然循环自动清洗式高产高效节能蒸发器

研究设计的自然循环自动清洗式高产高效节能新型蒸发器 ,加热室内安装有自动清洗螺旋 ,循环总阻力能够降低到 110 0 0Pa以下。沸腾室的特殊设计使循环母液能够在较大的深度处开始汽化 ,并且停留时间较长 ,比较充分地汽化 ,大幅度地降低出口动能损失 ,使自然循环的有效推动力高达 120 0 0Pa以上 ,不仅省去高能耗的强制循环泵 ,而且能够使蒸汽消耗大幅度降低 ,蒸发能力提高 30 %以上。     

ENERGY DISSIPATION DISTRIBUTION AND MIXING IN A TORUS REACTOR

Previous works devoted to the development of the swirl flow generated by rotation of the marine screw impeller in the loop toroidal reactor show that the flow structure is characterized by the existence of a secondary flow. The deformation of the axial velocity profile, due to the bends curvature and the rotation of the agitator, modify considerably the friction and the transfer near the wall. The objective of this work is to study the toroidal flow and to characterize the wall turbulence. The wall shear stress distribution in the torus were performed by using an electrochemical method. The measurements of the wall shear stress were carried out in the inner and outer walls. The evolution of the wall velocity gradient with the longitudinal distance depends on the location in the torus. These results allow to obtain information about the friction factor, which is compared with the one measured directly by using piezometric connections. The experimental determination of the axial dispersion coefficient is obtained by using the dispersion plug flow model with a total recirculation. Finally, a relationship between the turbulent characteristics and the mixing parameters has been established.     

鼓泡塔中Reynolds剪切力及涡扩散系数的局部分布

根据鼓泡塔内的两相湍流特性,提出估算塔内局部Ｒｅｙｎｏｌｄｓ剪切力的方法,由尼导出新的局部涡扩散系数关系式,讨论其与关系式的异同并与湍流实测数据比较。结果表明,新关系式给出与实测值更为一致的结果,而既有的一些关系式的计算值偏高,较之单相管流关系式,新关系式具有物理意义。