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Thesis Advisor张伟鹏 ; 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反应结晶 环流结晶器 氢氧化镍 机制


Other Abstract

Airlift loop reactors (ALR) are widely used in biotechnology and wastewater treatment, because of their efficient mixing and good mass/heat transfer characteristics. Comparing with the stirred crystallizer, there are no moving mechanical parts in ALR, and the shear rate is moderate and relatively uniform throughout the reactor volume. In view of these excellent properties, ALR has been considered as a new prospective crystallizer. However, few reports have been found in the literature for the study on liquid-liquid reactive crystallization.The objective of this work is to study the reactive crystallization in an ALR using the precipitation of Ni(OH)2 as a model reaction. Firstly, the spherical Ni(OH)2 particles are prepared by orthogonal experiments in an ALR. Then, the growth of Ni(OH)2 particles in an ALR and a stirred tank was quantified by scanning electronic microscope (SEM), X-ray diffraction (XRD), laser particle analyzer, tap densitometer and optical microscope, and the growth process of Ni(OH)2 particles is analyzed. It is found that the growth of Ni(OH)2 particle tap density mainly depends on the size of crystallites: the bigger the size of crystallites, the bigger the tap density is. Based on these, the growth process of Ni(OH)2 particles in ALR is elaborated. Crystallites precipitated from solution aggregate to form large particles with much void. These constituting crystallites continue to grow up, that takes up the void inside particles and makes the tap density increase.Then, the influence of the volume of ammonium hydroxide (VN), pH, feeding methods, the height of draft tube (Hd) and gas flow (qg) on the growth of crystallites in an ALR is explored. The main conclusions are as follows:(1) The size of Ni(OH)2 crystallites increases firstly and then decreases with the rising of VN, pH and Hd. When VN=300mL, pH=11.4, Hd=250mm, the size of Ni(OH)2 crystallites get to the maxium value.(2) The micro-mixing in gas disengagement zone is most efficient. The crystallites grow up quicker when feeding position is located here.(3) Gas flow has an important effect on the growth of crystallites. The Ni(OH)2 crystallites grow up bigger with the increasing of gas flow. 

Document Type学位论文
Recommended Citation
GB/T 7714
曹天荣. 气升式内环流反应器中反应结晶过程的实验研究[D]. 北京. 中国科学院研究生院,2017.
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气升式内环流反应器中反应结晶过程的实验研(5309KB)学位论文 限制开放CC BY-NC-SAApplication Full Text
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