关键词: 偏心搅拌, 漩涡运动轨迹, 漩涡深度, 聚氯乙烯, 混合时间

Abstract: The relationship of eccentricity ratio with the vortex motion trajectory, the depth of the vortex, the uniform drop-down velocity and the mixing time of CBY impeller were investigated. The experiments were carried out in a flat bottomed cylindrical stirred tank with the diameter 476 mm. The results showed that vortex center do linear motion and arc motion when eccentricity ratio before and after 0.45. The trajectory of the vortex center satisfies a certain law. The depth of the vortex is affected by the eccentricity ratio much more than rotational speed and material viscosity. In this experimental condition, the effect of eccentricity is 1.9 times of the speed to the drop rate of liquid level and 4.4 times of material viscosity. Vortex depth reduces as the eccentricity ratio increases. It satisfies certain linear rule. The uniform drop-down velocity of polyvinyl chloride with the diameter 4 mm increases first and then decreases as the eccentricity ratio increases. The eccentricity ratio at minimum inflection point is 0.4~0.5. The best eccentricity speed increased by 20.3% when the liquid level rises from 1.0T to 0.6T (T is diameter of stirred tank). Stirring power consumption is increased. Adding a single baffle will change the liquid flow field in the tank and make the vortex disappear. But in the same adding material position, the mixing time of full baffle is shorter than that no baffle 66.9%. The mixing effect was obviously enhanced.

Key words: eccentric mixing, vortex motion trajectory, vortex depth, polyvinyl chloride, mixing time