Research And Development Of Novel Wide Adaptability Agitator

The viscosity of reaction medium of reaction operation used in chemical, pharmaceutical and light industry, such as polymerization reaction, is changing with the reaction process, and the range of variation in a few mPa.s to a few Pa.s, so the agitator of reaction process should not only have good mixing performance, but also need to provide sufficient shear force. At the same time, in order to remove reaction heat timely, the heat transfer ability of agitator tank should be good. However, the traditional agitator can’t fulfill the requirements well, so a new large-double-blade impeller is designed, and its relevant parameters, such as its power, flow field and mixing, are obtained by the method of experimental combined with numerical simulation, which laid a good foundation for industrial application.In order to optimize the structure of the new agitator, the power characteristics and mixing characteristics experiments under0.8Pa.s and5Pa.s viscosity system are conducted. The results show that the optimal included angle between up and down blades is45°, the optimal distance from the bottom is50mm, the optimal number of grids is6, the optimal distance of up and down blades is25mm and positive rotation direction is better.In order to confirm whether the new agitator takes account of mixing, shearing and wide adaptability of media viscosity synthetically, double-deck MIG agitator and ribbon agitator which usually used in middle and high viscosity system are chosen as comparison objects. The experimental results show that the novel agitator costs less energy to obtain the same mixing effect than other agitators, whether in low or high viscosity system, its energy conservation advantage is very obvious.The Metzner constant of the optimal new agitator is84.283by using the Metzner-Otto experimental method in power-law liquid CMC(14.9%), it indicates the shearing force of new agitator is larger than double-deck MIG agitator and ribbon agitator in the same medium and rotating speed.Finally, this paper researches the flow field characteristics, power characteristics and mixing performances of novel agitator which has its optimal structure with help of CFD numerical simulation method. The results show that there are existing cycle flow of upper blades region cycle flow of down blades region and cycle flow of upper blades region to down blades region in agitator tank, and the simulation results of power characteristics and mixing performances are consistent with experimental data, which indicates it can be used in scale-up design of new agitator.