超声场下搅拌槽内微观混合

Micromixing inside stirred tank reactor in ultrasonic field

以醋酸锌、氯乙酸乙酯和氢氧化钠的平行反应为研究体系,考察了较高物料浓度时超声场下搅拌槽内的微观混合情况。结果表明:搅拌和超声波振荡对微观混合有明显的强化作用,在不同超声功率下,存在搅拌速率N对微观混合影响的临界搅拌速率Nc。当N>Nc时,搅拌速率对微观混合的影响可以忽略;N<Nc时,随搅拌速率提高,微观混合效果越来越好。根据实验结果拟合了微观混合时间和能量耗散率的关系,经过与卷吸模型所给出微观混合时间的关系式进行比较可知,高反应物浓度下微观混合效果较差。

The micromixing efficiency inside the stirred tank reactor in various ultrasonic fields was investigated on the basis of a unique parallel reaction system with zinc acetate, sodium hydroxide and ester chloroaeetate when the reactant concentration was higher. The results show that the micromixing can be enhanced via improving stir speed N and ultrasonic surging, and there exists a critical stir speed Nc at various ultrasonic powers. At N 〉 Nc, the effect of the stir speed on the micromixing may be ignored ; at N 〈 Nc, the micromixing efficiency gets better and better with the increase of the stir speed. According to the experimental result, the relation between the micromixing time and the average power consumption rate was correlated in this system. Compared with the relation given by the engulfment model, the efficiency of mieromixing is lower at higher reactant concentration.