热烟气环境下脱硫废水液滴蒸发特性研究进展

Research progresses on evaporation characteristics of desulfurization wastewater droplets in high-temperature flue gas

利用热烟气作为热源喷雾蒸发脱硫废水具有工艺简单、处理效率高等优点,但脱硫废水液滴蒸发机制不清是各种热烟气蒸发工艺存在的共性问题。本文综述了脱硫废水热烟气蒸发工艺中液滴(群)蒸发特性研究,首先介绍了脱硫废水液滴在高温烟气中的蒸发过程,指出其蒸发过程与纯水滴存在明显差异,原因在于盐溶液蒸汽压降效应及析盐成壳。进而分析了脱硫废水烟道蒸发工艺中液滴群蒸发实验研究现状,总结过程参数如烟温、烟速及废水水质对蒸发的影响。接着介绍了相关数值模拟研究及干燥动力学模型,用于获取工艺参数和不同水质脱硫废水蒸发特性的内在关联。同时为获得干燥动力学模型所需脱硫废水蒸发信息,简述了单液滴蒸发测试技术及其在含固含盐液滴蒸发中的相关研究。最后提出可将反应工程法模型耦合CFD精确描述脱硫废水液滴蒸发进程,将宏观尺度下液滴群蒸发信息和单液滴蒸发特性结合,揭示脱硫废水液滴蒸发的内在机制。

Utilization of hot flue gas for desulfurization wastewater treatment has the advantage of simple process and high efficiency.However,the imprecision of mechanisms of evaporation commonly exists in evaporation treatment technology.In this paper,evaporation characteristics of desulfurization wastewater droplets(group)and existing problems were summarized.Evaporation behaviors of desulfurization wastewater droplets were firstly introduced,elucidating discrepancy between pure instances and wastewater during the evaporation process was owing to the vapor pressure depression of saline solution and precipitation of the salt.Spray scale experimental studies on evaporation treatment technology for desulfurization wastewater by flue gas were summarized.Important factors including gas temperature,velocity and wastewater characteristics were concluded.To inquire about the essential relevance between operation parameters and different characteristics of wastewater,numerical simulations and drying kinetic models were discussed.Additionally,single droplet drying(SDD)technologies and their applications were reviewed,which helps obtain specific drying history of wastewater droplet and construct drying kinetics of desulfurization wastewater.At last,CFD coupled with the reaction engineering approach(REA)was expected to delineate the evaporation process of desulfurization wastewater well.It is advisable to combine the information of macroscopic spray evaporation and the results of single droplet drying,which may reveal the internal mechanism of evaporation of desulphurization wastewater.