涡轮自吸桨强化气液混合及氧化反应速率

自吸式搅拌桨具有强化多相及均相体系混合的特性，被广泛应用于化工冶金等领域。本文提出了一种新型涡轮自吸桨，并对其在混合及氧化还原过程中的强化作用进行了研究。以电导率法作为测定方法，以混合均匀时间作为表征参数，对搅拌转速、搅拌输入功率、示踪剂添加位置、吸气和吸液混合等影响因素进行了系统研究。研究结果表明，混合均匀时间随搅拌转速增加而降低，且存在临界转速，即为200r/min，当搅拌转速大于临界转速200r/min后，混合均匀时间基本维持稳定；当搅拌桨以吸气形式运转时，其他条件相同的情况下，自吸桨200r/min转速的混合效果与常规搅拌桨350r/min的混合效果相当；当搅拌桨以吸液形式运转时，自吸桨在0.27kW/m³输入功率下可达到常规搅拌桨1kW/m³以上输入功率的搅拌混合效果。同时，本文以水杨酸为活性氧捕集剂，初步探究了自吸式搅拌桨在强化氧化还原过程的机理，研究结果表明自吸式搅拌桨在吸气运转过程中，混合搅拌体系产生了羟基自由基，对应羟基化产物在120min后积累浓度为73.47μmol/L。此外，以二价铁为氧化剂受体，以二价铁的氧化效率为表征参数，对自吸式搅拌桨实际应用效果进行了系统研究，研究结果表明，在氧化二价铁的过程中，当pH为5.0时，自吸桨氧化优于曝气氧化效果；在pH=4.0、常温条件下，相较于普通搅拌桨，自吸式搅拌桨对应体系的氧化效率达到30%，是常规搅拌桨的10倍；当转速大于300r/min时，转速增加对氧化平衡终点影响较小，对氧化速率影响较大，即转速为400r/min的氧化效率比300r/min的氧化效率高30%。

Gas-liquid mixing and oxidation reaction rate enhanced by self-inducing impeller

Self-inducing impeller is characterized by enhancing the mixing of multi-phase and homogeneous phase, which is widely used in the fields of chemical engineering and metallurgical engineering. In this article, a new type of self-inducing impeller was presented and its application in enhancing gas-liquid mixing and accelerating oxidation reaction rate was investigated. The influences of agitation speed, power consumption, tracer addition location, gas and liquid self-inducing behaviors on the mixing time were studied. The mixing time was determined by the change of the conductivity of the solution. The results indicated that the mixing time decreased with the increase of the stirring speed and remained relatively stable when the stirring speed exceeded the critical speed of 200r/min. Under the same condition, the self-inducing impeller, operated in gas suction mode at 200r/min, performed similarly with the common impeller running at 350r/min in the mixing time. In addition, when the input power was 0.27kW/m³, the self-inducing impeller operated in liquid suction got same mixing effect as the common impeller for over 1kW/m³. At the same time, the mechanism of the self-inducing impeller in the process of enhancing redox reaction was preliminarily explored with salicylic acid used as active oxygen collector. The result showed that hydroxyl radical was generated during the course of operation of the self-inducing impeller and the concentration of corresponding hydroxylated product reached 73.47μmol/L after 120min. Moreover, the application effect of the self-inducing impeller was systematically studied with ferrous iron as oxidant acceptor and the oxidation efficiency of ferrous iron as characterization parameter. The result suggested that the oxidation efficiency of the self-inducing impeller was better than that of aeration when the pH was 5.0. Under the condition of pH=4.0 and the common temperature, the oxidation efficiency of the self-inducing impeller was up to 30%, which was 10 times that of the conventional impeller. When the rotation speed was more than 300r/min, the increase of rotation speed had little effect on the end point of oxidation equilibrium, but had a great effect on the oxidation rate, that is, the oxidation rate of 400r/min was 30% higher than that of 300 r/min.