鸟粪石结晶流化床结构优化

Geometry optimization of struvite crystallization fluidized bed

针对鸟粪石结晶流化床结构设计的不确定性及复杂性,采用数值模拟的方法模拟多粒径体系下不同构型流化床的湍流强度、分级特性和微晶截留效率。模拟结果表明,一段式流化床对鸟粪石颗粒的分级效果及湍流条件均优于多段式和锥体式流化床;沉淀区内增设沉淀组件未能显著提升微晶截留效率。验证实验结果表明,在不同的进水磷浓度(240,480和1 000 mg·L-1)下,一段式流化床对磷的去除效果与传统的多段式流化床无显著差异,且具有良好的造粒效果,大于1.25 mm的产品占比分别为88.1%、96.4%和70.1%。实验结果验证了数值模拟优化方法的可靠性和合理性,简化后的一段式鸟粪石结晶流化床具备良好的磷处理效果及产品特性,是理想的鸟粪石流化结晶反应器。

In view of the uncertainty and complexity in the geometry design of struvite-crystallization fluidized bed reactors,numerical simulation was first adopted to explore the turbulence intensity,classification characteristics and fines entrapment behaviors of fluidized bed reactors with different geometries under multiparticle systems.The simulation results showed that the one-sectional fluidized bed reactor was superior to the multi-sectional and cone-shaped fluidized bed reactor in classifying pellets and turbulent conditions.The fines retention efficiency cannot be significantly improved by installing sedimentation components in the precipitation zone.As for the consequences of experiments,no significant difference of phosphorus removal efficiencies was observed between the one-sectional fluidized bed reactor and the traditional multi-sectional fluidized bed reactor at different influent phosphorus concentrations(240,480 and 1 000 mg·L-1).It was also proved that the onesection fluidized bed reactor had good capability in granulation,where particles with sizes larger than 1.25 mm took up the percentage of 88.1%,96.4%and 70.1%,respectively.The experimental results validated that the reliability and rationality of the numerical optimization method.The simplified one-section fluidized bed reactor,which displayed good performance in phosphorus removal and product characteristics,was a promising struvitecrystallization fluidized reactor.