HYDRODYNAMICS CHARACTERIZATION BY IMAGE ANALYSIS ON POOL SCRUBBING UNDER GLOBULAR AND JET INJECTION REGIME

Pool scrubbing has several applications in energy engineering, mainly as filtering systems for gaseous streams. Typical examples are tray towers, mobile bed scrubbers and fluidized bed scrubbers. The most relevant applications of pool scrubbing can be found in nuclear engineering where it is widely used as a source term mitigation safety device in nuclear power plants with light water reactors. In this study, we used image analysis to characterize the hydrodynamics in a scrubber using demineralized water and air as working fluids. The pool is 1.5 m in height, 1 m in length, and 0.5 m in width. Nozzles of 10, 20, and 50 mm diameter were used as a gas injector, and three air mass flow rates covering globular and jet injection regimes, 0.095 kg/s, 0.3 kg/s and 0.4 kg/s, were considered. The analysis of the images allowed to identify three main sections of the pool, characterized by different flow structures and conditions: the injection zone, the break-up zone and the rising zone. The injection zone includes the formation and detachment from the nozzle of the first stable bubble; in the break-up zone, the first bubble breaks into a swarm of smaller bubbles, and finally, in the rising zone, the bubble size distribution reaches a stable configuration with a high number of small ellipsoidal bubbles.