不同涡流场形态下混凝效能研究

Research on the efficiency of coagulation in the different vortex flow field

采用粒子成像速度场仪(PIV)对Taylor-Couette反应器中纯水力流场及添加不同混凝剂的混凝过程进行观测与研究,同时对比聚合氯化铝(PAC)、聚合硫酸铁(PFS)、三氯化铁(Fe Cl3)的混凝效能与化学条件、水力条件之间的相互关系.结果表明,几种絮凝剂的速度场都较接近于纯水力条件下的速度场,且在波状涡流场中混凝效能最好;Fe Cl3在较宽的转速范围内都能有较高的浊度去除率,而PFS在紊动强度稍大的流场中也能获得好的混凝效能.波状涡流场可为絮凝反应提供最佳的水力条件,而初期波状涡波较有利于产生大粒径絮体,可为后期絮凝反应提供更佳的水力条件.

Particle image velocimetry（ PIV） was applied to study the flow field and the coagulation efficiency under different hydraulic-chemical conditions in Taylor-Couette reactor. The effects of flow field on the coagulation of different coagulants including polymeric aluminum chloride（ PAC）,polymeric ferric sulfate（ PFS）,and ferric chloride（ Fe Cl3） were compared. The results show that the velocity vector fields obtained by the flocs were much closer to the ones obtained by tracer particles under the pure hydraulic condition. The efficiency of the coagulation in the wavy vortex flow was the highest. Therefore,wavy vortex flow field can provide the optimal hydraulic conditions for coagulation process. There were a higher turbidity removal rate in a wide range of the rotational speed during the coagulation process of Fe Cl3. But in the case of PFS,the highest efficiency was obtained in the vortex flow which has the slightly greater turbulence intensity than the wavy vortex flow. It was shown that the preliminary develop stage of wavy vortex flow is suitable for generating the flocs with large diameter,and providing better hydraulic conditions for later flocculation process.