Liquid entrainment from spray distributors for packed columns
A theoretical model has been developed for estimating the total entrainment from spray nozzles used in liquid distributors of packed beds. The model is based on a mathematical representation of the drop size distribution in sprays, and on the drop buoyancy equations. It takes into account flow rates and physical properties of the gas and liquid as well as the orifice diameter of the spray nozzles. An experimental investigation for measuring entrainment from sprays was conducted in a 17-inch air-water contactor with an 11.5-inch spray section using four types of spray nozzles at different air and water flow rates. Good agreement between experimental values of entrainment obtained in this work and the model predictions were generally observed. Model predictions were also compared with the limited amount of experimental data found in the published literature, for air-water and air-paraffinic oil (lsopar-M®) systems. The model was confirmed on the basis that it predicts total entrainment and does not allow for partial removal of entrainment by walls, adjacent sprays, or target devices such as liquid collector trays mounted above the spray nozzles. The total entrainment predicted by the model is conservative for multiple spray nozzle arrangements or where a target device is used.