Effect of gas distributors on hydrodynamics in molten-metal bubble column reactors for fluorinated gas removal using computational fluid dynamics

• Published in: Chemical engineering research & design 2024-08, Vol.208, p.436-445
• Main Authors: Ngo, Son Ich, Thi Hong Bui, Hanh, Lim, Young-Il, Lee, Uen-Do, Lee, Youngjae, Kim, Sung Won
• Format: Article
• Language: English
• Subjects: Computation fluid dynamics (CFD); Fluorinated gas (F-gas) removal; Gas distributor design; Hydrodynamic parameters; Molten-metal bubble column reactor (MMBCR); Semiconductor industry
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2024.06.032

Fluorinated gases (F-gases) emitted by semiconductor industry have high global warming potential. Repurposing F-gases into valuable metal fluorides using molten-metal bubble column reactors (MMBCRs) is a promising alternative for their removal. Many researchers have reported hydrodynamics of bench-scale MMBCRs using computational fluid dynamics (CFD). However, the effect of the gas distributor type on hydrodynamics in large-scale MMBCRs has not been addressed. This study investigated hydrodynamics of pilot-scale MMBCRs with different gas distributors in a N2-Sn system including 1 % CF4 by using a volume-of-fluid (VOF) CFD model. The VOF-CFD model was validated against the experimental bubble sizes in air-water and Ar-Fe systems. Using the CFD model, the gas holdup (αG), Sauter mean bubble size (d32), and specific interfacial area (as) of three gas distributors (20 spargers, and perforated plates without and with tip) were evaluated in the pilot-scale MMBCR at 650 °C. The bubble size distributions near the gas distributor were significantly different for the three MMBCRs but were similar in the upper zone of the reactor. αG and d32 were approximately 15 % and 22 mm, respectively. as for the three MMBCRs ranged from 55 to 59 m2/m3. The VOF-CFD model predicted the crucial hydrodynamic parameters for reactor design and optimization. [Display omitted] •A volume-of-fluid (VOF) CFD model was developed to evaluate hydrodynamics of MMBCR.•The VOF-CFD model was validated against bubble size experimental data.•Bubble characteristics were examined in N2/CF4-Sn MMBCRs with three gas distributors.•Sparger showed a higher interfacial area than perforated plates with and without tip.