Effect of Viscosity on the Performance of Twin-Fluid Injector for Modern FCC

The Fluidized Bed Catalytic Cracking process involves the conversion of hydrocarbon feed into valuable light products through vapor phase cracking. This process occurs in the presence of a hot regenerated catalyst. To initiate the cracking, the crude oil is atomized using an atomizer, forming small droplets at the bottom of a riser in the feed catalytic cracking unit. This study focuses on investigating the impact of viscosity on the atomization performance of a two-phase fan-shaped air blast atomizer. Compressed air, water, and glycerol/water combinations were used as the working substances in experimental experiments while maintaining a high liquid flow rate. The size and velocity distributions of the droplets were measured and quantified using a 2D Phase Doppler Particle Analyzer system. Additionally, the visualization of the spray in the large target area was achieved through backlight illumination imaging technique. The spray spread increases with an increase in air flow as well as liquid viscosity. Sauter mean diameter of the droplets appeared to remain constant or independent of viscosity at low air flow rates. However, as the air flow rate increased, the SMD of the droplets also increased. This indicates that viscosity has a minimal influence on droplet size at lower air flow rates but becomes more significant as the air flow rate rises. Furthermore, the study found that the mean velocity of the droplets increased as the air flow rate increased. Conversely, with an increase in the viscosity of the liquid, the droplet mean velocity decreased. This suggests that higher air flow rates positively impact droplet velocity, while increased liquid viscosity acts as a hindrance, resulting in reduced droplet mean velocity.