Numerical analysis of chevron demisters with drainage hooks in optimizing separation performance. (May 2020)

• Record Type: Journal Article
• Authors: Li, Shunyang; Wang, Pengfei; Luo, Xiangyu; Wang, Yucheng; Yang, Xuelong; Thakur, Amrit Kumar; Zhao, Wensheng
• Is Part Of: International journal of heat and mass transfer. Volume 152(2020)
• Publication Date: 2020-05
• Subjects: Chevron demister -- Separation efficiency -- Liquid film -- Droplets re-entrainment -- Computational fluid dynamics; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2020.119522
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A numerical study of chevron demisters with different hook configurations is carried out. Discrete phase model, EWF model and DRW model are applied to simulate the gas–liquid motion. Separation performances and film distribution are analyzed to find the ideal demister. The separation mechanism and re-entrainment mechanism of droplets are discussed. Abstract: Chevron demister is widely used in the industry program to remove the liquid droplets from gas flow. Design a demister with optimal separation performance (higher separation efficiency and lower pressure loss) is mainly concerned in the industry process. In this study, the separation performances of the four demisters (named as A, B, C, and D) are numerically evaluated and compared to find the ideal one. A combination of DPM, EWF model, and DRW model are used to simulate the motion of droplets in gas flow. Contours of velocity magnitude, pressure, particle tracks, and wall film thickness on vanes are obtained. Overall separation efficiency η, grade separation efficiency ηd and pressure loss ΔP are also discussed. It can be concluded that separation efficiency of type D is 17% higher than that of type A when inlet velocity v = 2 m/s, and becomes 3% higher when v = 10 m/s. Pressure loss increases 5178.2 Pa, 6278.2 Pa, 8621.1 Pa and 11, 450.2 Pa for type A, B, C and D respectively when v increases from 2 m/s to 10 m/s. Large droplets are mainly captured at the first two stages, as the velocity increases, the liquid film expands backwards and can be observed at the last two stages. Compared to double hook, single hook induces higher separation efficiency as well as pressure loss. Splashing and film stripping are the main reason of re-entrainment. The ideal type of chevron demister is related to the specified situation with respect to its separation efficiency and pressure loss.