Falling film co-current flow cyclone demister for separating high-boiling droplets: Gas-liquid flow pattern and performance

Abstract

In many processes, the product gas stream contains liquid droplets that easily condense or solidify, which can deteriorate demister performance and even block equipment during gas–liquid separation. We proposed a falling film co-current flow cyclone demister (F2CFCD) to solve the above problems. The novel idea is that an additional stream of solvent fluid is added to the gas stream containing the droplets. After injecting the demister, the solvent fluid forms a film on the wall of F2CFCD. When the droplets are separated to the wall surface by centrifugal force, they are dissolved by the liquid film, thereby avoiding crust formation. In this work, the gas–liquid flow characteristics and the performance of F2CFCD are investigated numerically and experimentally. A hot-wire anemometer (HWA) is used to measure the gas velocity, and a conductivity method is used to measure the liquid film thickness. A coupled numerical model of the RSM-DPM and Eulerian wall film (EWF) model is applied to discuss the effect of the gas–liquid flow rate on the flow field in the demister. The liquid volume flow rates ranges from 0.5–10.5 m3/h, and the gas volume flow rates range from 640–894 m3/h. The gas flow pattern and the liquid film flow regimes are explored in the F2CFCD. A film thickness model is established to evaluate the average film thickness in the waterfall regime. Experimental observations illustrate that F2CFCD has a high separation efficiency for droplets under all conditions.