Spheroidizing mechanisms and simulation of spherical silica in Oxygen-Acetylene flame

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Vol. 29; no. 3; pp. 789 - 795
• Main Authors: Hou, Huichao, Ji, Zhengjia, Xie, Zhong, Jin, Hongyun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2018
• Subjects: Finite element method simulation; Heat transferring; Oxygen-Acetylene flameprocess; Spherical silica powders; Spheroidizing mechanism; Oxygen-Acetylene flameprocess; Heat transferring; Finite element method simulation; Spherical silica powders; Spheroidizing mechanism
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2017.12.018

To reveal the heat transferring and spheroidizing mechanism of silica powders by Oxygen-Acetylene flame route, the finite element (FE) simulation method was employed. The temperature distribution of furnace was researched. During spheroidization process of silica powders, melting and vaporizing time has been calculated. Finally, the optimization of combustion conditions has been obtained by experiment and simulation. [Display omitted] •The finite element simulation method was employed to study spheroidizing process.•We obtained distribution of temperature in the furnace by simulation.•The surface temperature and melting time of different silica powders were calculated.•Experiment and simulation presented the best spheroidization at flow rate of 40 L/min. In order for heat transferring and spheroidizing mechanisms of silica powders in Oxygen-Acetylene flame to be observed, the experiments were conducted and the Finite Element (FE) simulation method was employed. It has been certified that powder spheroidization occurred only at molten states, primarily depending on two major factors: melting time and particle size. Various particle sizes and various process parameters were studied systematically, whereas following the spheroidization mechanisms were concluded. At a flow rate of 40 L/min, the spheroidization rate percentage of 20 μm silica powders reached the maximum value. At a flow rate of 45 L/min, melting time of all particles were lower than 0.08 s, where it was difficult for 40 μm sized or larger powders to be spheroidized, also sharp corners of bigger powders were still observed. SEM results also revealed that powder spheroidization was affected by flow rate. The silica particle heat transfer time inside the gas flame furnace was reported and compared to SEM results. Through comparative analysis, the simulation results were in agreement with experimental results. The numerical model was capable of particle melting time calculation and can be used in spheroidizing results prediction to a certain extent.