气液混合搅拌器组合的优化

研究了由3种基本搅拌桨类型(圆盘涡轮、上翻斜叶涡轮和下压斜叶涡轮)组成的9种搅拌桨组合在搅拌槽中的气液分散能力,得到了不同气体流速下优化的搅拌桨组合.     

挡板进气多级搅拌槽内的气—液分散特性

研究了挡板进气多级搅拌槽内的气－液分散流型、临界分散转速、搅拌功率、气含率和气泡停留时间。试验证明，这种结构的搅拌槽，比标准通气式搅拌槽具有更优良的气－液分散特性，并回归得到了搅拌功率、气含率和气泡停留时间的关联式。     

双层桨气液搅拌反应槽气液分散特性

采用搅拌功率与氧传质系数方法,对一双层桨搅拌反应槽的自吸分散和表面充气分散性能进行研究.比较了两种桨叶组合在两种分散方式下的气相分散临界转速、搅拌功率及两种桨叶组合自吸分散时的气含率和气液传质系数.结果表明,六叶圆盘直叶桨和六叶圆盘斜叶桨的组合在自吸分散时具有较优的分散性能.     

同心双轴搅拌器气液分散性能的实验研究

针对气液搅拌操作形式单一的现状,将框式桨和Rushton桨组成的同心双轴搅拌器与黏稠体系中的气液分散操作相结合,实验考察了转动模式、内桨转速、通气量和体系黏度等因素对其气液分散性能的影响。结果表明,与单相黏稠体系中同向旋转模式下的功率与混合性能均占优不同,同心双轴搅拌器在反向旋转模式下的气液分散性能相对更好;外桨转速不变时,内桨转速从100增加到300 r·min^-1,整体气含率提高94.3%,局部气含率也均有增大;通气量从0.4提高到1.2 m3·h^-1,整体气含率提高了72.5%,但局部气含率和气泡尺寸的增大不显著;体系黏度增加,气泡在釜内的停留时间加长,整体气含率单调增加。作为影响搅拌釜气液分散性能的重要参数,转动模式、内桨转速和通气量的确定还必须兼顾系统的功耗与混合效率,并避免发生气泛。     

开槽式圆盘涡轮搅拌器的气液分散特性

在直径为0.49 m的平底有机玻璃搅拌槽中,针对开槽式和未开槽式半圆形(SHY,HY)和抛物线形(SBTD,BTD)涡轮搅拌器进行研究,表明叶片开槽对气液二相体系中临界分散、通气功率和气含率(含气体积分数)的影响。结果表明:由载气到气泛测得的泛点比气泛到载气测得的泛点明显滞后;对比相同条件下2类搅拌器的通气功率和气含率,在相同通气准数下,开槽式搅拌器表现出功率消耗(Pg/P0)较未开槽搅拌器下降幅度增大,曲线形式改变明显的特点;在相同功耗下,开槽式搅拌器有气含率高的特点,以SBTD为例,其要高于BTD 3%左右,SHY也要高于HY。综合以上特点,开槽式搅拌器值得被推荐用于工业气液搅拌反应器中。     

搅拌槽中液—液分散的放大研究：Ⅰ.湍流液—液分散理论分析

研究了搅拌槽内流体的湍流结构,提出了各个子域的能谱函数表达式,利用能谱函数研究了搅拌槽内的液-液分散,得到了各个子域的液-液分散机理方程。液-液分散是悬浮聚合、液-液萃取和传质等过程的基础。本文根据前人的研究和实验测定结果,提出了不同波数域的能谱函数,并导出了液滴的分裂机理方程。     

搅拌槽内气液两相混沌混合及分散特性

传统Rushton刚性桨常应用于过程工业中搅拌反应器内的气液分散过程,但由于桨叶背后易形成较大的气穴,气液混合效果较差。为了提高搅拌槽内气液两相的混合效果,提出了一种刚柔组合桨强化气液两相的分散过程。利用LabVIEW软件处理刚性桨和刚柔组合桨体系中气液混合过程的压力脉动信号,通过Matlab软件编程计算最大Lyapunov指数（LLE）,分析气液混合体系的混沌混合行为,同时,对刚性桨和刚柔组合桨体系中的相对搅拌功耗、整体气含率、局部气含率进行测量。结果表明,在功耗为170 W,通气量为10 m³·h^-1条件下,与刚性桨相比,刚柔组合桨能够通过刚-柔-流的耦合作用促进桨叶能量的传递过程,提高搅拌体系的混沌混合程度,刚柔组合桨体系的LLE提高了8.89%。同时,在相同操作条件下,与刚性桨相比,刚柔组合桨能够有效提高相对搅拌功耗以及搅拌槽内的整体气含率和局部气含率,且搅拌槽内气体分散更为均匀。     

挡板进气多级搅拌槽内的气－液分散特性

研究了挡板进气多级搅拌槽内的气－液分散流型、临界分散转速、搅拌功率、气含率和气泡停留时间。试验证明，这种结构的搅拌槽，比标准通气式搅拌槽具有更优良的气－液分散特性，并回归得到了搅拌功率、气含率和气泡停留时间的关联式。     

搅拌槽内气——液体系的分散,传质和传热

综述了搅拌槽内气－液体系分散、传质和传热特性，比较了搅拌器类型、通气方式和多级搅拌器对混合性能的影响。对文献中观点的分歧进行了探讨，由此得到两个传质系数关联式，并揭示出给热系数随操作条件变化的机理。     

搅拌槽内气－液体系的分散、传质和传热

综述了搅拌槽内气－液体系分散、传质和传热特性，比较了搅拌器类型、通气方式和多级搅拌器对混合性能的影响。对文献中观点的分歧进行了探讨，由此得到两个传质系数关联式，并揭示出给热系数随操作条件变化的机理。     

有蛇管的釜中多层桨的气液分散特性研究

有蛇管的釜中多层桨的气液分散特性研究葛张华，王志坚，张孝平，张秀娟（南京金陵石化公司设备研究院，２１００４６）关键词：气液分散，搅拌反应器，多层桨，放大１前言气液系统的搅拌广泛应用于吸收、化学反应和发酵中。其关键在于气体的分散和气液界面传质。气体的分...     

搅拌槽内的液-液临界分散

在φ391mm搅拌槽中,分别采用双层Brumagin桨、双层三叶后掠式桨和双层A310桨与7种内构件相组合,在无乳化剂下对油水比(质量比)分别为1∶1.5,1∶2.0的煤油-水体系的液-液临界分散进行了研究。从工业实用的角度出发,对前两种桨找到了一种可替代“轻液挡板”的小挡板及其安装方法:内冷管上均布4块小挡板,B/D=0.08,插入液面深度为0.2D。在φ188mm搅拌槽中,于全挡板条件下,以歧化松香皂为乳化剂,分别采用3种不同几何参数的双层Brumagin桨对油水质量比为1∶1.5的煤油-水体系的临界分散进行了研究。结果表明,与无乳化剂情况相比,液-液临界分散转速(N_c)下降30％～40％,临界分散功耗(P_(cv))下降53％～66％;桨径减小会使N_c和P_(cv)增加。     

LIQUID PHASE MIXING IN MECHANICALLY AGITATED VESSELS

Liquid phase mixing and power consumption have been studied in 0.3, 0.57, 1.0 and 1.5 m i.d. mechanically agitated contactors. Tap water was used as liquid phase. The impeller speed was varied in the range 2-13.33 r/s. Three types of impellers namely disc turbine (DT), pitched turbine downflow (PTD) and pitched turbine upflow (PTU) were employed. The impeller diameter to vessel diameter ratio was varied in the range of 0.25 to 0.58. The effect of impeller clearance from tank bottom was also studied. Mixing time was measured using the transient conductivity measurement.

The PTD impeller was found to be the most energy efficient for mixing in liquid phase alone. Further, PTD (T/3) was found to be most energy efficient as compared with other impeller diameters. The effect of clearance was found to be design dependent and it was found to be diameter dependent in the case of pitched turbines.

Flow patterns of different impellers have been studied by visual observations (using guide particles). These observations were supported by the measurements using Laser Doppler Velocimetry. A model has been developed for the prediction of mixing time. In the case of all the three impeller designs, a fairly good agreement was found between the predicted and experimental values of mixing time.     

DETERMINATION OF THE MIXING RATE OF A HIGH VELOCITY FEED STREAM IN AGITATED VESSELS

In semi-batch or continuously stirred reactors, often a feed containing one or more reactants has to be mixed with the contents of the vessel. For fast competitive or consecutive reactions the mixing rate of the feed stream with the vessel contents has a large influence on the product quality. The mixing rate is often controlled by the turbulent dispersion process. Therefore, it has been suggested in the literature to keep the turbulent dispersion time constant upon scale-up to obtain a constant product quality. In this study, based on a combination of a theoretical model, Planar Laser Induced Fluorescence experiments and Laser Doppler Velocimetry experiments, the turbulent dispersion coefficient is determined. This has been done for the case that a feed stream is mixed in a stirred vessel by a combination of feed stream and stirrer generated turbulence. The turbulent dispersion coefficient is used to derive an equation for the turbulent dispersion time as function of several design and process variables.     

DETERMINATION OF THE MIXING RATE OF A HIGH VELOCITY FEED STREAM IN AGITATED VESSELS

In semi-batch or continuously stirred reactors, often a feed containing one or more reactants has to be mixed with the contents of the vessel. For fast competitive or consecutive reactions the mixing rate of the feed stream with the vessel contents has a large influence on the product quality. The mixing rate is often controlled by the turbulent dispersion process. Therefore, it has been suggested in the literature to keep the turbulent dispersion time constant upon scale-up to obtain a constant product quality. In this study, based on a combination of a theoretical model, Planar Laser Induced Fluorescence experiments and Laser Doppler Velocimetry experiments, the turbulent dispersion coefficient is determined. This has been done for the case that a feed stream is mixed in a stirred vessel by a combination of feed stream and stirrer generated turbulence. The turbulent dispersion coefficient is used to derive an equation for the turbulent dispersion time as function of several design and process variables.     

通气式搅拌釜功率消耗的探讨

评估了通气式搅拌釜较有代表性的搅拌功耗关联式，指出大气穴形成之前，气体再循环将导致关系联式预测值偏离实际值４０％以上。用气体再循环系数对关联式进行修正，可得到适用于装有涡轮搅拌器的低粘体系的新的搅拌功耗关联式：当Ｇ≤２．５４时，Ｐｇ／Ｐ０＝０．７１Ｇ－０．８０；当Ｇ〉２．５４时，Ｐｇ／Ｐ０＝１．０；式中，Ｇ＝（Ｎｐ０／Ｎｐ０＾＊）＾０．６（ｄ／Ｄ）＾０．１５Ｆｒ＾０．０５［（１＋α）Ｎｑ］＾－０．     

有蛇管的釜中气液机械搅拌的功率研究

比较了挡板和蛇管对搅拌功率的影响关系，并在Ф４７６和Ф７８４两台几何相似的有蛇管釜中，采用六直叶圆盘涡轮，详细研究了不同液体中搅拌功率与通气量，桨径，桨层数，液位等因素的关系，由回归分析法得不通气时桨的功率准数Ｎｐ为Ｎｐ＝２．４（Ｄ／Ｔ）－０．３２．ｎ０．５１．（Ｈ／Ｔ）０．５７通过时的搅拌功率计算式为Ｐａ＝１．６６（Ｐ０＾２．Ｎ．Ｄ＾３／ＱＧ＾０＾．＾５＾６）０．４１当在Ф１０００釜中安置三层圆     

翼形轴流桨用于液液分散的冷模研究

翼形桨是新一代高效轴向流叶轮。本文将这类叶轮用于液液分散的冷模试验，测定了基本流型及其造成的液滴大小分布，研究了分散特性与搅拌功率的关系，并与传统叶轮比较了搅拌混合的综合性能。