搅拌器在工业合成醋酸反应器中的应用

详细分析了工业合成醋酸反应器中的机械搅拌过程,描述了气液分散搅拌过程中搅拌桨叶的选择和计算。对醋酸反应器这样复杂的气-液反应混合过程,必须采用合适的机械搅拌器。目前采用最多的是径向流和轴向流相结合的多层搅拌桨叶组合形式的搅拌器。搅拌桨的计算和设计对保证醋酸反应中充分的气-液分散混合并达到良好的气-液传质过程十分重要。不同大小醋酸反应釜的搅拌器必须根据不同生产处理量和醋酸装置的工艺条件进行设计和选型。     

关于搅拌设备设计中的几个问题

针对搅拌设备设计中有关搅拌功率、搅拌槽的传热和固液悬浮搅拌的问题 ,通过自身的设计实践 ,对其中的相关内容和参数 ,提出自己的看法     

多相搅拌槽内宏观混合研究进展

多相搅拌槽反应器广泛应用于化工、冶金等过程工业中,而多相混合状态对于多相搅拌槽反应器的设计、优化和放大具有重要意义.混合时间是表征其宏观混合过程的一个重要参数.文中从实验和数值模拟二方面对多相搅拌槽反应器的液相混合时间研究进行综述,对气液、液固、液液、气液固4种体系的多相搅拌槽进行了分类总结,讨论了分散相、桨型、转速、...     

发酵中的搅拌技术

本文结合搅拌的基本原理和气液过程搅拌的特点,阐明了如何正确、合理地设计搅拌机.     

土壤修复中固液混合过程的研究及应用

以土壤修复中淋洗混合过程为研究目标,使用自有设备开展了液固混合过程实验,以混合效果和单位质量能耗为目标函数,以混合比例、搅拌桨形式、搅拌转速以及搅拌时间等操作参数为考察变量,通过设计均匀实验,并利用DPS软件对实验结果进行数据处理,并经过实验验证,得到最优固液混合操作条件为搅拌桨类型为铲式,液固混合质量比为0.5,搅拌速度为70 r/min,搅拌时间为10 min,得到的平均混合度为0.94,单位质量物系功耗为12.1 kg/kJ。     

气液固三相搅拌的临界转速

考察了搅拌桨型、挡板和气体分布器对气液固三相搅拌混合的临界转速的影响 ,并回归了临界转速关联式 ,可用于指导工业过程的设计和放大。     

医药中间体催化氢化反应搅拌器的设计

针对医药中间体催化氢化过程,通过计算与分析确定了搅拌反应器型式,并进行了工业化对比。根据工业化运行的情况,验证了氢化搅拌的传质要以考虑反应物料为主,有的反应过程强化气液传质反而对反应不利,该脱保护基氢化反应过程应采用弱吸气的搅拌强化气液传质,选用了表面曝气搅拌器。工业化应用验证了设计思路的正确性,可供氢化工业化设计参考。     

卧式搅拌釜气液传质性能研究

在 50L卧式搅拌釜内,采用氧电极法测量纯水 O2 体系的液侧容积传质系数kLa, 研究搅拌弗鲁德数Fr、桨叶尺寸和液含量等对kLa的影响。随着Fr提高,kLa增大;桨径、桨宽、叶片数和层间距与kLa有关系,而层间夹角对kLa影响不大;随液含量的增加kLa先缓慢升高而后降低,且峰形和峰值随Fr的增大而发生变化。研究结果可供四氟乙烯等聚合釜搅拌桨设计优化和工程放大参考。     

搅拌罐内固液两相流数值模拟研究现状

搅拌罐作为一种搅拌混合设备广泛应用于石油、化工、生物、造纸等行业,搅拌的类型可以是固液、液液、气液等多相流动问题,在石化行业中,固液搅拌比较常见。本文综述了搅拌罐内固液两相流数值模拟的方法,从固体颗粒浓度、搅拌功率、搅拌时间三个方面概述了国内外搅拌罐固液两相流数值模拟的研究现状,为搅拌罐的结构优化和工况优化提供了理论支撑。     

高粘度液混合浅述

<正> 高粘度液的混合通常是以捏合或搅拌来完成。是工业上广泛应用的单元操作。如涂料工业中的厚漆、腻子、铅笔漆、浮雕漆以及塑料、油墨、合成纤维、橡胶、石油、化妆品、制药、食品、造纸和水泥等许多工业部门都不乏要用到捏合和搅拌设备。实践证明对于高粘度液的混合,合理选择和设计搅拌翼形对于强化传热,提高混合质量,改善被混合介质的性能是至关重要的。     

Transitory powder flow dynamics during emptying of a continuous mixer

This article investigates the emptying process of a continuous powder mixer, from both experimental and modelling points of view. The apparatus used in this work is a pilot scale commercial mixer Gericke GCM500, for which a specific experimental protocol has been developed to determine the hold up in the mixer and the real outflow. We demonstrate that the dynamics of the process is governed by the rotational speed of the stirrer, as it fixes characteristic values of the hold-up weight, such as a threshold hold-up weight. This is integrated into a Markov chain matrix representation that can predict the evolution of the hold-up weight, as well as that of the outflow rate during emptying the mixer. Depending on the advancement of the process, the Markov chain must be considered as non-homogeneous. The comparison of model results with experimental data not used in the estimation procedure of the parameters contributes to validating the viability of this model. In particular, we report results obtained when emptying the mixer at variable rotational speed, through step changes.     

Mixing of concrete or mortars: Dispersive aspects

This article describes an experimental methodology offering mixing efficiency criteria for granular materials in terms of their dispersion capability. This methodology is based on the analysis of the dispersion kinetics of colored, cohesive, tracer particles that progressively disagglomerate during stirring. The effects of certain critical parameters such as the mixer speed and the type of mixer are described. In terms of the mix design, the contribution of the largest particles to the dispersion kinetics, and therefore to the mixing efficiency, is highlighted. A simple comparison of the mixing efficiency of mixer/mix design/procedure sets is finally provided for such cementitious granular materials.     

Comparative Study of Clogging in Valve and Cascade Mixers

A cascade mixer and a valve mixer were applied for the precipitation of CaCO₃. This model reaction has been used for benchmarking both mixer types with respect to their robustness against fouling. The valve mixer was found to be much less susceptible to fouling and clogging. Pressure changes during precipitation in both types of mixers differed significantly. This parameter can be easily used for identification of clogging in the valve mixer and applied as input in clean‐in‐place (CIP) procedures. The pressure trend in the cascade mixer is quite complex and, therefore, difficult to apply for CIP. Ultrasonic treatment has been evaluated as a measure to prevent clogging.     

氯醇化管道反应新工艺的压降和传质的研究

氯醇化管道反应新工艺是环氧丙烷生产过程中关键步骤，该反应属气液非均相系统，但装有Ｋｅｎｉｃｓ型静态混合构件的管道反应器用于气液系统还缺乏大量的基础数据。研究以Ｎ２－Ｈ２Ｏ２作为实验系统，测定了不同工况下压降和氧含量，并应用一心均相模型救是了相应的摩擦系数和传质系数。     

Numerical analysis of flow in close-clearance mixers

A numerical procedure was developed to compute the streamlines and the shear rate distribution for the flow of Newtonian and “power-law” liquids between a mixer arm and the vessel wall. The results show that the geometry of the mixer has an overriding influence upon the extent and distribution of shear whilst inertia and the shear-dependent viscosity play only a minor role.     

圆排波瓣喷管引射器高效掺混流场数值计算

采用贴体曲线坐标、SIMPLEC算法和完全压力修正,在非正交性非常大的结构型同位网格上求解了圆排波瓣喷管引射器内流场的不可压Navier-Stokes方程,湍流采用标准k-ε涡黏模型.计算得到了引射器中热混合效率沿混合管轴向的变化规律和流向涡的演变规律.混合管中的流向涡阵列大大强化了主次流的掺混.但该型引射器的总体热混合效率不高,实验的3种主流温度下最大热混合效率为0.874.将混合管出口截面速度分布和温度分布的数值模拟结果与实验值比较,两者比较一致;模拟结果与混合管沿轴向的静压系数分布规律实验值也基本相同.     

A method for measuring the imbibation rate of powder in a liquid

Mixing of powders into liquids is a common unit operation. Mixing can be divided into several steps: imbibation of the powder into the liquid being the first. Under some circumstances, for instance, if the powder has poor wetting properties, imbibation can be the rate-determining step. In this study imbibation in a commercial mixer was studied and a method to measure powder imbibation in a model that simulates the commercial mixer was developed. The imbibation mechanism in the commercial mixer is based on a wave drawing the powder down into the liquid, and surface flow transporting it towards the wave. A wave imbibation model was constructed based on the same mechanisms, in which physical parameters such as wave height, surface velocity and surface residence time could be varied. An experimental procedure was used to determine the maximum imbibation rate. Measurements were found to have good reproducibility, with a standard error of means of 4.7% for spray-dried sodium caseinate. The maximum imbibation rates were found to be of the same magnitude in the commercial mixer and the wave imbibation model: 0.04 kg/s m in the commercial mixer and 0.06–0.16 kg/s m in the wave imbibation model for spray-dried sodium caseinate powder.     

Mixing of concrete or mortars: Distributive aspects

This article describes an experimental methodology offering efficiency criteria for granular materials in terms of their mixing distributive capability. The methodology is based on analyzing the distribution kinetics of colored tracer particles which were demonstrated to respond similar to cement particles during mixing. The effect of certain critical parameters such as the mixer type, the volume and the mixer speed are investigated. The influence of mix design characteristics on distribution is also presented for several mixer types. Finally, a comparison of the dispersive versus the distributive capability is achieved for several (mixer, mix design) systems, which opens opportunities for defining rules for transfer and extrapolation.     

高转速、无稳心搅拌装置介绍

本文介绍了一种特殊的高转速、无稳心搅拌系统，具备简洁、高效、稳定、安全的特点，经使用证明，效果良好，性能可靠，为高速搅拌及无稳心反应釜的应用提供了一条新的设计及运用的途径。     

低浓度煤层气发电用发动机混合器的设计

介绍了一种新混合器的设计、特点及其工作原理,并对试验结果和原混合器进行了分析,结果表明新的混合器不仅能满足不同浓度燃气的需求,而且降低了燃料消耗,该混合器主要用于低浓度煤层气发电用发动机。