Forming and stripping of the wall film and the influence on gas–liquid separation

Abstract The paper aims to investigate re‐entrainment mechanisms of wall films. The computational fluid dynamics method was adopted to study the gas–liquid separation process considering the wall film model. The interaction between the droplets and gas was solved by Euler–Lagrange method, whereas the forming and stripping of the wall film was studied by Eulerian wall film model. The results reveal that superficial velocity affects the re‐entrainment significantly, and there is a critical superficial velocity determining the occurrence of wall film stripping. According to this work, the critical velocity for air continuous phase is 11.2 m/s. It is found that the discrete phase content and droplet size have no effect on film thickness but affect the separation efficiency. The molecular viscosity and the density of continuous phase affect the Eulerian wall film on two aspects. First, the critical stripping velocity decreases with the increase in molecular viscosity. Second, the film average thickness and separation efficiency decrease with the increase in the product of viscosity and density of the continuous phase. Because the high velocity causes some unsteady of the results, the bulk velocities lower than 20 m/s are recommended. The development of re‐entrainment mechanism provides a good understanding of inertia separation.