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Thesis Advisor杨超
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword搅拌槽 硫酸钡沉淀 微观混合 双层桨 实验
Other Abstract

不互溶的液-液两相搅拌槽广泛应用于石油、聚合、制药等工业生产中。搅拌槽内的混合状况,尤其是微观混合,决定了产品的质量和选择性。现有的用于表征微观混合的模型反应,由于存在反应物或生成物易溶于有机相的情况,无法用于液-液搅拌槽中。硫酸钡沉淀反应是快反应,对微观混合敏感,因此,可以作为模型反应来研究液-液搅拌槽内的微观混合状况。流动影响混合过程,继而影响化学反应结果,通过沉淀颗粒平均直径大小以及尺寸分布,能够考察不同操作条件对混合的影响。本论文采用直径为240 mm 的双层搅拌桨操作的平底圆柱有机玻璃槽,以煤油(或者硅油)为分散相,氯化钡水溶液为连续相,采用硫酸钠与氯化钡沉淀反应来表征液-液复杂体系中的微观混合效应。以一定的进料速率将硫酸钠溶液加入到搅拌槽内,进料结束后在搅拌槽侧壁取样,对所获得的沉淀产物进行分析。实验考察了桨型、桨间距、进料位置、桨组合以及表面活性剂等操作条件对液-液搅拌槽微观混合的影响。实验结果表明:在不互溶的液-液两相搅拌槽中,当上层桨选用RDT(Rushton disk turbine),下层桨选用PBTU(Pitched blade turbine upflow),无论在进料位置A还是B加料,硫酸钡沉淀颗粒的平均粒径均随煤油体积分数的增大呈现先增加后减小的趋势;添加表面活性剂可以显著降低硫酸钡沉淀颗粒的平均直径,同时使平均直径分布更加集中,而不加表面活性剂时,颗粒的尺寸分布较宽。 


Two immiscible liquids dispersion in stirred tank reactors is a very common industrial operation, widely used in petroleum, polymerization, food, and pharmaceutical industries. The product property and selectivity depend on the mixing, especially the micro-mixing. The common used “model reactions” cannot be used to study the micro-mixing in the liquid-liquid stirred tank, because the reactants or the products can be dissolved or absorbed by the oil phase. The precipitation of barium sulphate is also a fast reaction process, which is sensitive to the mixing. So the average particle size and size distribution can be used to reflect the micro-mixing conditions in the liquid-liquid stirred tank. In this work, the effect of micro-mixing on the precipitation process in a liquid-liquid stirred tank with double impellers is experimentally investigated. The diameter of the tank is 0.24 mm. The barium chloride aqueous solution is used as the continuous phase and kerosene as the dispersed one. The investigations mainly contain the effects of operating conditions, such as impeller speed, feed position, oil volume fraction, surfactant, on the BaSO4 precipitation process. The main experimental results shows that: in the liquid-liquid stirred tank using the combination of RDT (the upper impeller) and PBTU (the lower impeller), the mean particle size increases first and then decreases with the increase of oil volume fraction; Adding the surfactant into the immiscible liquid-liquid system, the average particle size decreases, and the particle size distribution is more concentrated compared with the condition without surfactant. 

Document Type学位论文
Recommended Citation
GB/T 7714
段永鸿. 沉淀反应法研究液-液搅拌槽内微观混合[D]. 北京. 中国科学院研究生院,2015.
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