高速混合制粒机的混合制粒机理与流场研究

通过模拟实验装置的流场研究，分析了立式双轴三步湿法混合制粒机的制粒机理，并指出各主要参数与结构设计要点，据此研究而开发的ＧＨＺ型高速混合制粒机，已成功地应用于医药、食品、化工催化剂、粉末冶金、农药、化妆品、洗涤剂和染料等行业。     

制粒机混合影响因素研究

目的：研究制粒机中影响混合效果的各个因素,以及混合过程中不容易混匀的点。方法：采用控制变量法,分别对制粒刀速度、搅拌桨速度、混合时间和装载量进行研究。结果：制粒刀速度、搅拌桨速度、混合时间和载料量对混合效果有显著的影响。     

挡板对自浮颗粒混合的实验研究

考察了１２种挡板组合对搅拌釜中自浮颗粒混合的影响,发现标准挡板不利于自浮颗粒的下拉,挡板的空间布置对搅拌混合也有很大的影响,仅用挡板系数不足以完整地表示挡板的作用。     

搅拌釜内气液自浮颗粒三相体系混合的功耗研究

对搅拌釜内气液固（自浮颗粒）三相体系混合的功率消耗进行了测量,研究了搅拌浆组合、档板组合和气体分布器对功耗的影响,对较佳的搅拌浆组合、挡板组合和气体分布器回顾了功耗经验并联式,用于工业放大过程。     

气固并流系统中弥散颗粒混合行为的研究

采用磷光瞩拉瞬态点源注入示踪技术，研究了气固并流系统中弥散颗粒的轴、径向混合行为，并引入二维扩散模型加以描述，收到了良好的效果。对在气固并流上行和下行系统中的研究进行对比表明：在两种系统中弥散颗粒的轴、径向混合行为类似．研究还给出了在实验条件下气固并流上行系统弥散颗粒的轴、径向Peclet数的关联式．     

自浮颗粒的搅拌混合

综述了近２０年来自浮颗粒的固液两相悬浮和气液固三相分散的研究结果,并与下沉颗粒体系的规律作了比较,发现自浮颗粒三相分散规律与下沉颗粒的三相分散规律存在奶多差别。前者的悬浮难点在液面,要求搅拌浆能提供液面是上推式的流型,而后者的悬浮难点在釜底,要求搅拌浆能提供釜底是下压式的流型。     

水泥浆混合能量对其性能影响的实验研究

在固井施工过程中,水泥浆是处于不断混配的过程,混合能量对水泥浆的综合性能有所影响,从而影响到固井质量。水泥浆在高速率混合时,类似于在恒速搅拌器内高剪切速率的流动状态;在管内流动低速率混合时,类似于在六速旋转粘度计内低剪切速率的流动状态。因此,基于室内恒速搅拌器和旋转粘度计的实验过程分析,推导出旋转粘度计测试液体过程混合能量的计算式,并通过对水泥浆进行室内实验认为:水泥浆混合过程在混合能量为10-15kJ/kg区间时,流性指数呈现最高值,稠度系数呈现最低值;在水泥浆混合阶段增加水泥浆的混合能量有助于提高水泥石的强度;并建议在水泥浆混配过程中,先进行几分钟高速搅拌,再实施注水泥施工,这有助于提高水泥浆性能的稳定性,有利于注水泥过程中的顶替和水泥石强度的提高。     

新型穿流搅拌釜的研究(Ⅰ)混合机理

对设有开孔挡板的新型穿流搅拌釜的混合机理进行了研究.从理论上分析了固液混合机理和影响其混合效果的搅拌釜结构参数,得出了提高混合效果的关键是强化涡流扩散的结论;然后着重研究了挡板的开孔对固-液体系混合时间、临界悬浮转速、功率消耗和旋涡深度等影响的机理.研究认为设置开孔挡板所产生的射流卷吸能强化涡流扩散,有利于湿法磷酸搅拌反应釜内固体粒子与其周围流体的热质传递,从而有利于磷矿粉的充分分解和磷石膏的良好结晶.     

新型穿流搅拌釜的研究(Ⅱ)混合性能

通过讨论开孔挡板系数对固液系统混合时间、临界悬浮转速、搅拌功耗、量纲1混合时间和旋涡深度的影响,研究了设置有新型穿流挡板搅拌釜的混合性能,确定了其较佳的构型,以完善其在湿法磷酸生产中的应用.     

高速混合制粒机制粒过程

应用高速混合制粒机对湿法制粒过程进行了研究。单因素实验结果表明,混合时间对混合均匀度影响较明显,混合时间过长,将出现混合均匀度下降的现象;随黏合剂质量分数增加大颗粒增加,小颗粒减少,颗粒度有所增加;剪切桨转速变化对粒度分布的影响较小;搅拌桨转速变化对粒度分布的影响较明显,随着搅拌桨转速的增大,目数大于20目与小于100目的颗粒都有明显减少的效果。     

穿流式刚-柔组合搅拌桨强化混合澄清槽内油-水两相混沌混合

运用LabView和Matlab软件分别采集和处理穿流式刚-柔组合搅拌桨扰动澄清槽中油-水两相流体内部的压力脉动信号,得出的最大Lyapunov指数（LLE）和多尺度熵（MSE）,反映流体内部的混沌程度;同时采用流场可视化技术观测流体混合状态。结果表明,相比于刚性组合桨,穿流式刚-柔组合搅拌桨通过穿流孔与柔性部分的共同作用改变流场的结构和能量耗散方式,使流体的混沌程度和混合状态都优于刚性组合桨。当转速为88 r·min^-1时,流体的混沌混合都达到最佳状态,各实验条件下的LLE均大于零,表明流场混合体系已进入混沌状态,且穿流式刚-柔组合搅拌桨体系的MSE明显高于刚性组合桨体系,说明穿流式刚-柔组合搅拌桨的混合效果优于刚性组合桨。另外,柔性片上穿流孔的数目和柔性桨叶的厚度对流场的混沌特性也有明显的影响。     

HFO旋转人字板机构的工作原理及结构简述

HFO旋转人字板为环形结构，它的支撑环增加了两个惰辊，每一个支撑环都有一些定位孔，以保证惰辊与气垫辊准确定们；四个叠加的支撑环把惰辊和气垫辊包围在其中，加强了结构的稳定性和灵活性；冷却装置采用车间外空气，以避免堵塞气垫辊的内孔。用此系统替代原来的旋转机头，解决了吹制塑料薄膜过程中，薄膜打褶、周边厚不均等问题。其制造成本较低，性能价格比高，操作维修方便。     

Experimental study on geometric structure of isolated mixing region in impeller agitated vessel

Isolated mixing region in agitated vessel with rotated two-bladed paddle impeller and no baffle was visualized experimentally and its structural property was investigated in detail. A set of thin filaments spirally wrapping around the core of the toroidal isolated mixing region is observed under low Reynolds number conditions, which is smaller than 60. Three-dimensional geometrical structure of filament in isolated mixing region depends on the periodical perturbations caused by the rotating impeller. We have succeeded in the determination of three-dimensional geometrical structure of filament in isolated mixing region based on relation between the movement of fluid particle and filament numbers and/or wire turns. Interestingly, the wire turns of filaments are opposite to movements of fluid particles.     

浆叶对固液混合效果的影响

在固液混合装置中，对不同角度圆盘涡轮式斜叶叶轮，圆盘涡轮式弯叶叶轮进行了实验研究，考察了其在混合过程中对混合时间和搅拌功率的影响。实验表明，这种固液混合装置中涡轮式弯叶叶轮混合效果最好。     

Effect of impeller type on the mixing in torus reactors

Torus reactors are characterized by a homogeneous fluid circulation without dead zones. Torus reactors were used for applications in biotechnology, food processing, polymerization and liquid waste treatments. The relatively simple extrapolation of performances, due to the absence of dead volume, is one of the main advantages of this reactor, with low shear stresses and an effective radial mixing allowing efficient heat dissipation. This study is based on the mixing in order to analyse the fluid circulation, mainly in turbulent flow regime, and to characterize the torus reactor with the axial dispersion plug flow model. The objective of this study is to characterize the flow and the mixing in the torus reactors in batch and continuous modes. The mixing analysis was made according to the flow parameters and to the geometrical characteristics of the reactor and impeller. The mixing in the torus reactor can be characterized by the Péclet number, Pe_D, defined with torus diameter. A representative model based on plug flow with axial dispersion and partial recirculation was proposed.     

双重兑卤法生产低钠光卤石工艺研究

针对盐湖卤水生产光卤石存在生产周期长、产品氯化钠含量高、反应废液污染环境等问题,基于Na⁺,K⁺,Mg²⁺//Cl^-—H₂O四元体系相图理论,采用双重兑卤法进行低钠光卤石生产实验研究,通过控制兑卤比例和陈化时间等因素实现高效快速生产光卤石。研究结果表明,第一次兑卤实验中,钾饱和卤水与老卤质量比为1∶1.8、陈化时间为4 h,反应液中钠离子的去除率达59.30%,钾离子的损失率为9.58%;第二次兑卤实验中,钾母液与老卤质量比为1∶1.7、陈化时间为3.5 h,反应液中钾离子的收率为62.69%,钠离子的收率为8.55%,析出固相光卤石的质量分数为96.96%,氯化钠的质量分数为3.04%;且整个实验过程无需投加浮选药剂。该法生产周期短、产品质优、对环境友好,为盐湖生产光卤石提供了不同的思路。     

The effect of mixing aids on the kinetics of mixing in a rotating drum

The batch mixing of particulate solids in a rotating drum mixer has been investigated with various numbers of Lucite balls added as mixing aids. Two experimental systems have been studied. One involved the mixing of dolomite particles of two sizes, 28 × 32 and 42 × 48 mesh, while the other consisted of mixing calcite and silica of the same size range, namely 65 × 100 mesh. The progress of mixing was followed by a simple sampling and assaying technique which permits accurate determination of the composition of the powder in sections along the axis of the mixer. The role of mixing aids on the mixing process was quantified by evaluating their effect on the diffusion coefficient and the degree of mixedness. An empirical relationship between the diffusion coefficient and the number of balls added to the mixer was obtained.     

Characterisation of impeller driven and oscillatory mixing by spatial and temporal shear rate distributions

Computational fluid dynamics (CFD) technique was used to model spatial and temporal behaviour of flow patterns in an impeller-driven stirred vessel (IDSV) and in an oscillatory flow baffled vessel (OFBV). The spatial and temporal shear rate distributions were assessed for IDSV based on k-ε model, appropriate for classical mixing, while the distributions for OFBV were calculated based on large eddy simulation suitable for oscillatory flow mixing. In addition, the real parameters of the vessels such as geometry, physical dimensions, impeller speed, oscillation frequency and amplitude, and density and viscosity of the fluid (water), were taken into account. Under given operating conditions the spatial shear rate distribution appears to be quite distinct for two different methods of mixing. For OFBV, the volume-averaged shear rate was found to be of one order of magnitude larger than that of IDSV. In addition, a marked distinction between the temporal shear rate distributions was observed. In OFBV, the modelling shows that particles spend most of their residence time in the high shear regions, while in IDSV, particles reside mainly in the region of considerably lower shear rates.     

Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

The effects of impeller eccentricity and Reynolds number on the mixing performance were studied for Rushton turbine stirred tank systems operated in the laminar regime (Re < 10). A digital image analysis of an acid–base decolourization reaction was used to characterize the mixing efficiency. Results show that both parameters have remarkable effects on the destruction of the toroidal segregated regions surrounding the Rushton turbine in laminar flow. Criteria are given to prevent the formation of these segregated regions in a tank. It is also shown that shaft eccentricity does not impact on the impeller power consumption.     

Transient instability of the flow induced by an impulsively started rotating cylinder

The onset of instability induced by transient momentum diffusion in a boundary layer over an impulsively started rotating cylinder is examined. Kirchner and Chen (J. Fluid Mech. 40 (1970) 39) have conducted experiments and reported anomalously large Taylor numbers of up to 20×10⁶, far exceeding the well-known value of 1708 for Taylor vortices in steady flow. In this paper, we argue that it is inappropriate to treat the phenomenon as a steady-state wide-gap Couette flow, because the unstable boundary layer in their experiments was very thin. The instability in the fluid induced by momentum diffusion is an unsteady-state phenomenon analogous to transient thermal instability, whose mathematical equivalence for the steady-state cases have been established by Taylor (Philos. Trans. R. Soc. London A 223 (1923) 289). We find that the onset of instability can be predicted from a transient Taylor number defined as Ta=y⁵(∂u/∂y)²/ν²R_i. The maximum transient Taylor number is found to occur at a critical depth , where Ta_max=1.461U_i²(νt)^1.5/ν²R_i. Ta_max bears a theoretical critical value of 1100 from linear stability analysis. The experimental data of Kirchner and Chen (J. Fluid Mech. 40 (1970) 39) agree remarkably well with this value. The critical time can thus be predicted with good accuracy from a critical value of the maximum transient Taylor number of 1100. The theoretical critical dimension of the toroidal plume formed after the boundary layer becomes unstable is found to be , which agrees well with measurements. The average critical dimensionless wavenumber of the experiments of Kirchner and Chen (J. Fluid Mech. 40 (1970) 39) is found to be 3.05, which is very close to the theoretical value of 2.9.