高粘度液体真空搅拌脱泡理论分析与计算

Mechanism Analysis and Simulation of Vacuum Agitating Deaeration of High Viscosity Liquids

真空搅拌脱泡是高粘度液体的一种有效脱泡方式。对于高粘度液体中的气泡,单靠自身的浮力上升,其速度是极其缓慢的,搅拌槽内生成的气泡主要依靠搅拌被带到近液面而逸出。建立了搅拌流场中的气泡运动方程,获得了气泡在流场中的相对运动速度。计算了气泡从液面逸出的总时间。真空搅拌脱泡过程主要发生在液面,论文分析了搅拌槽内真空度大小、主流体循环到液面的次数和主流体在液面停留时间对脱泡的影响。为保证气泡在近液面有足够的停留时间挣脱液面张力,必须要有一个合理搅拌转速。

The mechanisms,responsible for bubble formation and removal from high viscosity liquid by vacuum agitating deaeration,were theoretically analyzed and simulated.The impacts of the liquid surface,pressure of the container,the structure of the double cone spiraling vacuum agitator,on the formation and motion of the bubbles were studied.The simulated results show that the stirring of the agitator generates and brings the bubbles up to the liquid surface of the high viscosity liquid,instead of spontaneous formation and floating to the surface because of buoyancy.The motion equation of the bubbles in the rotating field was formulated;the relative velocity and the total time for a bubble to escape from the surface were evaluated.We found that three major factors：the pressure in the vessel,number of turns and staying time on the surface of the main liquid body,strongly affect the vacuum deaeration.We suggest that the stirring speed be optimized so that the bubble has enough time to free itself from the surface tension.