Comparison of bubble velocity, size, and holdup distribution between single‐ and double‐air inlet in jet microbubble generator

Abstract

AbstractThe jet microbubble generator is often used to produce bubbles in flotation equipment, which generates microbubbles by self‐absorbing or inflating. Bubble behavior is a dominant factor in froth flotation, and its velocity, size, and distribution greatly affect flotation performance. However, the asymmetry distribution of the pressure, bubble velocity, and gas holdup in generator with single inlet probably causes eccentric wear to the equipment. Therefore, in this study, using particle image velocimetry (PIV), high‐speed dynamic camera, and computational fluid dynamics (CFD) technology, the bubble behaviors in the jet microbubble generators with single inlet and double inlet was studied. The results show that under air flux of 0.4 L/min, the change of bubble diameter (D32) in two generators is obvious, reducing by 5.97% and 3.77% under circulation water flux of 1.5 and 2.5 m3/h, respectively. Comparing the influence of circulating water fluxes, the double‐inlet structure can reduce the bubble diameter more effectively. The maximum turbulent dissipation rate in the throat section of the generator with double inlet is greater than 120, while it is less than 100 in single‐inlet structure. For bubbles in generator with double inlet, velocity difference in radial direction reduces to 0.03 m/s and is more symmetrical. Meanwhile, the double‐inlet generator can also optimize the uniformity gas holdup distribution, which is beneficial to increase the collision probability of flotation and reduce the abrasion of microbubble generator.