2.3 Study on the morphology and motion of microbubbles under different parameters
A. Operational parameters. Three operational factors including pressure, gas-liquid ratio and length of the release pipe were selected for orthogonal test (3×3) to determine their effects on the particle size of microbubbles. The specific working conditions are shown in Table 1. The test process is as follows: The microbubble air flotation equipment was set and operated in turn under 9 kinds of condition according to Table 1. (1) Start the device. When the liquid level reaches H=400 mm, the high-speed photography system is started to shoot the rising process of microbubbles near H=400 mm. Stop flooding when the liquid level rises to H=450 mm, and the shooting time is 60s. (2) Clean the device. After one shooting, open the drainage valve at the bottom of the air floating column to drain the water, and start the device again to clean the air floating column, so as not to affect the following test results. The dynamic video was observed, and the particle size of bubbles was measured and counted. The proportion of bubbles with particle size ≤50 μm was taken as the experimental index to clarify the relationship between the main factors and the microbubble particle size distribution and obtain the optimal working condition.