Theoretical research on collision behavior and production evolution of titania particles in an industrial oxidation reactor of chlorination process

doi:10.11949/0438-1157.20241476

Abstract

Abstract:

As one of the main processes for synthesizing titanium dioxide (TiO₂), the chloride process has the advantages of large output, high degree of automation and good quality. Based on operating parameters and structural dimensions of industrial titanium oxidation reactor in chlorination process, the TiO₂ particles evolutions, including oxidation, nucleation, collision and the sintering, were studied in this paper. The results indicate that the vapor-phase oxidation reaction of TiCl₄ is the dominant mechanism in the oxidation reactor. Following the oxidation reaction, TiO₂ molecules act as precursors for nucleation, with a characteristic nucleation time of approximately 4.44×10^-¹³ s. For TiO₂ particles smaller than 600 nm, Brownian motion is the primary mechanism driving particle collisions, while for particles larger than 600 nm, turbulence becomes the dominant mechanism. The initial particle size within collision-induced agglomerates is approximately 50—100 nm. These results will provide a theoretical support for the establishment of particles balance model in the industrial titanium oxidation reactor.

Key words: titanium dioxide, collision, agglomeration, nucleation, sintering

摘要：

氯化法作为合成钛白粉（TiO₂）的主要工艺之一，具有产量大、自动化程度高和质量好的优势。以工业级氯化法钛白合成氧化反应器结构尺度及运行参数为基础，对氧化反应器内TiO₂颗粒的氧化、核化和碰撞等动力学事件以及TiO₂颗粒碰撞后的烧结过程进行了研究。结果表明，TiCl₄气相氧化是氧化反应器内的主要反应过程，氧化后生成的TiO₂分子瞬间（核化特征时间约为4.44×10^-13 s）成为凝结核；布朗运动是粒径≤600 nm TiO₂颗粒碰撞的主要机制，湍流作用是粒径>600 nm TiO₂颗粒碰撞的主要机制；碰撞后形成团聚体中初始粒径为50~100 nm。研究结果可为工业级真实反应器内颗粒群平衡模型的建立提供理论支撑。

关键词: 钛白粉, 碰撞, 团聚, 成核, 烧结

CLC Number:

TF 823

Chenrui MA, Xiang WANG, Minhang SONG, Jun JING, Qiong WU, Yun HUANG. Theoretical research on collision behavior and production evolution of titania particles in an industrial oxidation reactor of chlorination process[J]. CIESC Journal, 2025, 76(7): 3316-3324.

马谌睿, 王翔, 宋民航, 敬军, 吴琼, 黄云. 氯化法钛白氧化反应器内颗粒碰撞行为及生成演化过程理论分析[J]. 化工学报, 2025, 76(7): 3316-3324.

Figures/Tables 11

Fig.1 Configuration of the chlorination process titania reactor

Fig.2 Particle formation and growth processes in the reactor

Fig.3 Reaction rate constants of oxidation reaction

Fig.4 Characteristic time of oxidation reaction

Fig.5 Critical radius of nucleation of TiO2

Fig.6 Nucleation rate and characteristic nucleation time of TiO2

Fig.7 Variation of Knudsen number with particle size of TiO2

Fig.8 Variation of Stokes number with particle size of TiO2

Fig.9 Variation of coagulation kernel with particle size of TiO2

Fig.10 Agglomeration formed by collision of TiO2 particles

Fig.11 Characteristic collision time of TiO2 particles

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