Single Orifice Effervescent Atomizer in simulated Counter–flow Conditions

article in a collection out of WoS and Scopus

en

CO2 is the most severe greenhouse gas released into the atmosphere and is responsible for the global temperature increase. The amount of CO2 released can be reduced through deployment of post-combustion CO2 capture. Spray columns, as simple gas cleaning contractors, utilise different types of atomizers e.g. pressure atomizers, twin fluid atomizers and rotary atomizers. The CO2 capture process requires well-tailored spray characteristics, such as mean drop size, drop size distribution, droplet density, spray cone angle (SCA) and droplet velocity. Effervescent atomizers are beneficial, in that way they can be used for spraying viscose chemical solutions to counterflowing flue gasses. However, they typically create a wide droplet size distribution. Small droplets from this wide distribution are carried away by the ambient flow and cause significant sorbent losses. The total surface area, which determines the rate of mass transfer of CO2, is significantly reduced by this droplet drift. In this study, the effervescent atomizer was tested under realistic flow conditions relevant to spray columns. A small-scale vertical wind tunnel was used to simulate flow velocity in the range from 0 to 10 m/s with a turbulent intensity lower than 3%. Phase Doppler anemometry and high-speed visualization were used to capture the droplet behaviour at several axial locations from the atomizer exit orifice. The liquid discharge was not influenced by the ambient flow. The effect of ambient flow was more prominent far from the atomizer, where the droplet momentum rapidly decreased. Droplets smaller than 20 µm were completely carried away by the ambient flow.

CO2 is the most severe greenhouse gas released into the atmosphere and is responsible for the global temperature increase. The amount of CO2 released can be reduced through deployment of post-combustion CO2 capture. Spray columns, as simple gas cleaning contractors, utilise different types of atomizers e.g. pressure atomizers, twin fluid atomizers and rotary atomizers. The CO2 capture process requires well-tailored spray characteristics, such as mean drop size, drop size distribution, droplet density, spray cone angle (SCA) and droplet velocity. Effervescent atomizers are beneficial, in that way they can be used for spraying viscose chemical solutions to counterflowing flue gasses. However, they typically create a wide droplet size distribution. Small droplets from this wide distribution are carried away by the ambient flow and cause significant sorbent losses. The total surface area, which determines the rate of mass transfer of CO2, is significantly reduced by this droplet drift. In this study, the effervescent atomizer was tested under realistic flow conditions relevant to spray columns. A small-scale vertical wind tunnel was used to simulate flow velocity in the range from 0 to 10 m/s with a turbulent intensity lower than 3%. Phase Doppler anemometry and high-speed visualization were used to capture the droplet behaviour at several axial locations from the atomizer exit orifice. The liquid discharge was not influenced by the ambient flow. The effect of ambient flow was more prominent far from the atomizer, where the droplet momentum rapidly decreased. Droplets smaller than 20 µm were completely carried away by the ambient flow.

Effervescent Atomizer, Counter–flow Conditions, Phase Doppler anemometry, High-speed visualization

28.10.2022

10