对撞流反应器甲醇合成实验研究

液相法甲醇合成由于有惰性液体介质的存在,气液相间传质对反应起到了一定的阻碍作用,对撞流反应器使用喷嘴将催化剂浆料雾化从而强化了气液相间传质。文中在对撞流反应器内对甲醇合成温度、合成气比例、气流量、浆料循环量以及喷嘴个数进行了考察,结果表明,温度控制在230℃左右操作比较适宜,二氧化碳参与反应对甲醇合成较为有利,合成气流量在22.4 L/min以后时空产率几乎不再增加,增加浆料循环量和采用对置式二喷嘴或四喷嘴比单喷嘴时空产率和出口甲醇体积分数都有所增加。由结果可知,利用喷嘴雾化和液体对撞可以显著地增强气液传质从而达到增加液相甲醇合成时空产率的目的。     

液-液萃取及新型液-液-液三相萃取机理研究进展

根据新型液-液-液三相体系的特点,对传统两相溶剂萃取、双水相萃取机理研究进展进行了综述,提出应用Lewis酸碱理论对两种萃取体系的萃取机理分别进行归类,评述了新型液-液-液三相体系研究进展并对其研究方向进行了展望。     

多射流锥形对撞流气流床流场特性实验及模拟研究

为了考察多射流锥形对撞煤加氢气流床内的冷态流场情况,以3 t/d的热态煤加氢气化炉为依据建立了气流床冷模装置。使用三维动态颗粒分析仪(3D-PDA)对气流床内的速度场进行了测量,同时使用Fluent软件,采用κ-ε模型对气流床内的流动情况进行了模拟研究,模拟结果与实验结果能较好地吻合。结果显示:多射流锥形对撞气流床内的流体流动分为对撞区、射流区、回流区和管流区,在考察范围内,随着进气速度的增加,回流区的体积占比先增大后减小;随中心喷嘴携带气速度的增加,射流区速度增大,且较进气速度的影响更为敏感;适当增加进气角度,则会降低射流区速度,增大回流区体积。     

液-液多相流微萃取的数值模拟和实验分析

运用Comsol软件对带有十字形和圆柱形辅助结构的微通道内两相层流进行了有限元分析。同时，以硫酸铜溶液为水相，被260^#溶剂油稀释30%的DZ988N萃取剂为有机相，并以光滑微通道为参照，开展了相关的液-液萃取实验。当给定流速在(0.5×10^-3) ~(5×10^-3) m/s范围内，圆柱形辅助结构能够促进水相中Cu²⁺的扩散，萃取效率最高，均能达到90%以上；而十字形辅助结构时而促进时而抑制水相中Cu²⁺的扩散，萃取效率不稳定，最高89.8%，最低74.6%。实验中，微通道内的两相为层流，如不考虑化学反应，Cu²⁺的扩散则仅依靠其浓度梯度差，扩散效率可表征萃取效率。有限元计算得到的扩散效率与实验获取的萃取效率值吻合良好，进一步得出了两相流场分布等流动特征，以解释不同辅助结构下的扩散效率差异。     

三股对撞式撞击流反应器的流动特性

采用高速数码相机对喷嘴直径1 mm的开放式三股对撞式撞击流反应器内的流场特性进行研究,考察了入口雷诺数Reinj、对置两管喷嘴间距d1、垂直管喷嘴到对置两管的垂直距离d2对流场特性的影响. 结果表明,在物料流量比为2时,Reinj对流体结构的影响较显著. 随Reinj增加,流体结构由链状向类似伞状变化,最终破碎成液滴,无规则向四周分散,雾化程度显著增加,撞击面边缘剧烈扰动,提供了较好的混合效果. 较小的d1使撞击区域接近对置两管喷嘴处,可能导致喷嘴堵塞而影响混合效果. 增大d2及Reinj=1699时,重力影响使流体结构由链状轻微向面积较小的伞状结构变化. 采用碘化物-碘酸盐平行竞争反应体系,物料流量比为8时,与传统撞击流反应器相比,三股对撞式撞击流反应器的离集指数约为其1/2,显示出优越的微观混合性能.     

三股对撞式撞击流反应器微观混合性能研究

采用高速数码相机对三股对撞式撞击流反应器不同入口雷诺数下的流场特征进行了研究,并采用碘化物-碘酸盐平行竞争反应体系,考察了不同喷嘴直径下的入口雷诺数、不同溶液体积流量比对离集指数的影响。结果表明:入口雷诺数、溶液体积流量比对离集指数有明显的影响。增大入口雷诺数,三股流体高速撞击破碎成的液滴粒径逐渐减小,液滴雾化程度增加,离集指数减小,微观混合效果增加;增大体积流量比,溶液局部浓度增大,导致混合不均匀,离集指数增大。与传统撞击流反应器相比,三股对撞式撞击流反应器离集指数为传统撞击流反应器的2/5,表现出了较好的微观混合性能,更适用于不等溶液体积流量比的液液快速混合反应。     

苯加氢工艺萃取蒸馏与液-液萃取的比较

本文对粗苯低温加氢两种萃取工艺特点从工艺、经济两大方面进行比较。分析了两种工艺流程,动力消耗,产品质量等,比较出各自的不同和相似之处。     

对撞式流化床超细气流粉碎机分级叶轮有限元分析

为解决对撞式流化床超细气流粉碎机分级叶轮力学性能分析的难题,提出了一种有限元数值模拟分析方法,并针对一直径为220mm,转速为7000r.min-1的分级叶轮,详细介绍了有限元分析过程,给出了分级叶轮叶片上的综合应力分布云图及沿叶轮长度方向的应力分布曲线。该分析方法可以在同类结构的应力分析中推广应用。     

气-液-液喷射反应萃取制备过氧化氢的过程

引　言过氧化氢 (H2 O2 )是一种性能优良的氧化剂 ,因其以水为还原产物而备受绿色化学与化工研究领域广泛关注 .以过氧化氢为氧化剂的氧化过程具有反应条件温和、选择性高、无污染等优点 ,因此被广泛地用于纺织品和造纸的无氯漂白、化学合成、污水处理等领域 ,应用前景十分广阔 ,市场潜力非常大 .蒽醌衍生物自动氧化法 (AO )是过氧化氢的主要生产方法 ,基本原理是[1] :烷基取代的蒽醌 (主要是 2 乙基蒽醌 )和四氢蒽醌 (主要是四　氢 2 乙基蒽醌 )溶解在适当的溶剂中配制成工作液 ,循环交替氢化和氧化工作液 ,即工作液中的蒽醌与氢气反应…     

新型流液道调节闸及其提升装置

本文通过对流液道调节闸板的工况条件和使用要求的分析,着重阐述了新型流液道调节闸板及其提升装置的结构特征和工作原理。     

一种新型的撞击流吸收器的设计研究

利用撞击流和平推流的优点,开发出一种新型的撞击流吸收器。对该吸收器进行了停留时间分布实验研究。利用清水吸收空气中CO2,对该吸收器的吸收性能进行了研究,实验结果表明,“全混流 平推流”流动特点的撞击流吸收器的吸收率明显高于鼓泡式吸收器,具有一定的推广与应有价值。     

Investigation of a two impinging-jets contacting device for liquid-liquid extraction processes

A two impinging-jets contacting device (TIJCD) for liquid-liquid extraction processes was proposed and tested through the standard test system recommended by the European Federation of Chemical Engineering (EFCE), toluene-acetone-water, as a typical example of liquid-liquid extraction processes. The results obtained for the overall volumetric mass transfer coefficient (capacity coefficient) were more than three times higher than those reported in the conventional contactors and in an air-driven two impinging-streams contactor. These experimental results clearly indicate the greater performance capability of TIJCD relative to those of conventional contactors. To have a perfect study on the pertinent parameters of the TIJCD, the influence of jets momentum, nozzles diameter and the inter nozzle distance have been investigated. In addition, the enhancing effect of the impingement zone has been studied using a non-impinging-jets contacting device. Based on the experimental data obtained, an increase in the liquid flow rates results in an increase in the extraction efficiency and overall volumetric mass-transfer coefficient, while increasing the distance between nozzles decreases the extraction efficiency. In addition, it was found that the effect of nozzle diameter on the extraction efficiency could be dependent upon the jets velocity.     

Physical behavior of highly deformable products during convective drying assessed by a new experimental device

ABSTRACT

This article presents an experimental device specially designed for the continuous measurement of mass and dimensions of samples submitted to convective drying. This experimental device consists of a magnetic suspension balance and an image acquisition system. The sample deformation is determined by image correlation using a custom software. The entire system is able to achieve accurate mass and dimension measurements over a wide range of temperature and relative humidity. To present the potential of this equipment, experimental data of highly deformable food products (potato and apple) submitted to several drying conditions are presented. The obtained results confirm that it is required to consider the actual sample surface to determine the mass flux. This allowed a first drying stage to be observed for potato. Clear differences in physical behavior of these two vegetable products were also observed, for example, an isotropic shrinkage behavior for potato and an anisotropic behavior for apple. These results were explained by the anatomical structure of the products.     

水平对置双向液体撞击流的振荡特性

利用平面激光诱导荧光(PLIF)技术对水平对置双向液体撞击流流场进行了实验研究,考察了等动量下撞击面驻点在不同喷嘴间距、不同进液流量下的稳定性和振荡特性。结果表明,撞击面驻点的振荡并没有一个固定的周期,并且频率主要集中在低频,而其幅度集中在0.1d～0.5d范围内:在L∈[1d,3d](L为喷嘴间距,d为喷嘴直径)范围内,振荡幅度随着L的增加而增大;在L∈[3d,5d]范围内,振荡幅度随着L的增加而减小。同时,撞击面的振荡幅度并不会随着流速的增大而一直增大,而是在达到一个峰值后逐渐降低。撞击面驻点的这种振荡特性对混合和传质具有一定的促进作用。     

经过表面处理的BHB250Y型填料在液液萃取中的应用

研究了规整填料的形状和特点,提出了合理改进方法,对填料表面进行光滑处理,应用于液液萃取单元操作中,采用新填料,提高了分离效率,解决了原来因分离物系中含有固体颗粒和杂质而堵塔的难题。结果表明,新填料到达了提高产量、提高分离效率以及克服堵塔的效果,带来了很好的经济和环境效益。     

倾斜式对喷流除尘效率影响因素的正交实验研究

针对水平式对喷流结构会使部分粉尘颗粒黏附在喷嘴对面的器壁上而导致除尘效率降低的问题,采用倾斜式对喷流除尘技术收集硫酸铵和硝酸铵混合物粉尘.对影响除尘效率的5个主要因素喷嘴速度、含尘浓度、喷嘴水平间距、倾斜角度和喷雾化水润湿含尘气流的耗水量,各作了4个水平的考察,得到了该条件下的最优方案喷嘴速度26 m/s、含尘质量浓度0.60kg/m3、喷嘴间距0.2 m、倾斜角度40°、耗水量0.21 kg/kg粉尘.实验表明该条件下的除尘效率最高可达96.8%,而且喷雾化水润湿含尘气流对除尘效率影响最大,倾斜式对喷流能有效避免粉尘颗粒粘附在器壁上.     

The atomization of a liquid sheet by an impinging air stream

An investigation has been carried out into the processes of drop formation from liquid sheets of controlled thickness by an air blast at approximately 90°. The results may be summarized as follows:

• 1.A liquid sheet does not break down upon immediate impact with the air stream but is deflected away from it. Waves are initiated at the point of impact and the sheet breaks down into drops through the formation of unstable ligaments.
• 2.The resulting drop size is a function of, inter alia, the sheet thickness. Thus the production of thin liquid sheets is an essential pre-requisite to fine atomization.
• 3.A semi-empirical relation has been derived which satisfactorily correlates mean drop size with sheet thickness for a wide range of operating conditions.
     

Learning control of a pulsed liquid-liquid extraction column

Liquid-liquid extraction has proved to be a very competitive technique compared to conventional separation methods such as distillation. It allows a higher degree of extraction, separation and concentration of the desired products to be obtained. Generally, a liquid-liquid extraction column is run manually. This, however, is not satisfactory, especially concerning new valuable applications in the field of fine chemistry where processes must reveal themselves flexible and polyvalent. The objective of this study was to improve the quality of control even with poor a priori information on the process and thereby to maintain the column in its optimal behaviour zone. This optimal behaviour has been shown to be reached for flooding conditions which can be controlled by measuring the conductivity of the liquid medium at a place located at the bottom of the column (below the distributor), the pulsing action being the command variable. The column considered is modelled as a random medium and the search tactics for the control problem are formulated as those of automation behaviour in a random medium. The automation is considered to be stochastic with a varying structure. This control approach requires minimum possible a priori information on the process. Usually the developed model of chemical plants is static or very complex and cannot be used to derive a control strategy. The experimental results illustrate the efficiency of learning control.     

非等温液-液对置撞击面温度分布均匀性

对不同条件下非等温过程液-液对置撞击后形成的气液混合撞击面的温度分布均匀性进行了研究。以温度不均匀系数和撞击面温度分布作为评价标准,利用Mixture模型数值模拟撞击过程,并基于平面激光诱导荧光（PLIF）技术进行可视化测量实验验证计算模型。通过对不同的喷嘴出口速度（v）、喷嘴对置间距（L）以及湍动能等条件下撞击面温度分布进行研究。结果表明,喷嘴直径和喷嘴对置间距一定时,增加喷嘴的出口流速,则温度不均匀系数整体呈下降趋势;喷嘴直径和喷嘴出口流速一定时,非等温液-液对置撞击后形成区域温度场分布随喷嘴间距的增加,其温度分布区间呈减小趋势。L=3D时,温度的分布区间最小,温度场分布最均匀。湍动能的分布曲线越平稳,液-液对置撞击后形成的气液混合撞击面的温度分布越均匀。