Re-entrainment in and optimization of a vane mist eliminator

Abstract The mechanism for breakup of a thin film on a vertical curved wall under the effect of airflow shear is studied as the main reason for re-entrainment in a vane mist eliminator. A force-balance model in boundary layer flow is established to illustrate the thin-film breakup mechanism. A theoretical formula is deduced for the critical airflow speed that results in film breakup in a corrugated-plate (CP) channel. This formula is related to the fluid properties of the film and the airflow, the wall-film thickness, and the structure of the CP channel. An experimental study is undertaken to establish the critical airflow speed for wall-film breakup in different CP channel structures. Planar laser-induced fluorescence (PLIF) is used to measure the film thickness on the CP. The relationship between wall-film thickness and Reynolds number is studied first. On that basis, the relationship between wall-film thickness and critical airflow speed is studied in different CP channel structures. The experimental data are consistent with the theoretical predictions and show that a thicker liquid film requires a lower critical airflow speed, at the same time, film surface fluctuations accelerate the film breakup. Combining theoretical and experimental data, it is proposed that the structural factor k 1 and the gas–liquid property factor k 2 determine the criteria for the breakup of the liquid film, and obtain an optimal angle based on k 1 .The optimum bending angle of the CP is 26.6°, this giving the highest critical airflow speed.