Twin-Fluid Nozzle for FCC Riser: Atomization and Spray Dynamics

Fluidized Bed Catalytic Cracking is a key conversion process in most refineries, transforming low-value heavy components of crude oil into high-value light products. The FCC unit consists of two main reactors—a riser and a regenerator. Typically, vacuum gas oil (VGO) serves as the feedstock, which is converted into valuable products such as LPG, gasoline, and diesel. The feed nozzle system, located at the base of the riser, injects VGO as liquid droplets. These droplets come into contact with a hot regenerated catalyst drawn from the regenerator, ensuring efficient mixing. Effective atomization from the feed nozzles is crucial for maximizing contact between the hydrocarbon feed and the catalyst. Most modern FCC nozzles are twin-fluid atomizers, which utilize pressurized gas to enhance fuel atomization. This study focuses on the spray characteristics of a specially designed nozzle for riser applications. A detailed experimental analysis is conducted to determine the optimal operating parameters for the nozzles. The section-wise averaged Sauter Mean Diameter decreases with increasing Air-to-Liquid Ratio (ALR) and closely follows a log-normal distribution. However, the overall section-wise average droplet velocity does not appear to follow a normal distribution.