脱硫废水旋转喷雾蒸发与旁路烟道蒸发特性研究

针对旋转喷雾和旁路烟道两类高温旁路烟气蒸发技术工艺，开展脱硫废水蒸发特性对比实验，结合可视化荧光示踪法及单液滴蒸发试验研究了废水雾滴在高温烟气中的蒸发过程，分析了烟气温度及烟气停留时间对蒸发性能的影响，并比较了两类废水蒸发工艺的差异。结果表明：脱硫废水液滴接触热烟气后将迅速失去表面自由水分，表面成壳固化为半干颗粒；旋转喷雾蒸发塔内主蒸发区域温度迅速降低，提高烟气温度有助于提升蒸发效率，降低出口灰分含水率；通过适当增大干燥塔尺寸，延长高温烟气在干燥塔内停留时间，可提升热量利用率，实现低气液比条件下的蒸发干燥；两类旁路蒸发工艺相比，旋转喷雾蒸发因雾化效果较好、气液混合均匀，蒸发性能略优于旁路烟道工艺。

Study of Evaporation Performance Between Centrifugal Spray Evaporation and Bypass Flue Evaporation to Treat Desulfurization Wastewater

To investigate the high-temperature bypass flue gas evaporation technologies including centrifugal spray evaporation tower and bypass flue evaporation, spray evaporation experiments were conducted using desulfurization wastewater. Evaporation process of wastewater droplets was revealed by the fluorescent tracer technique and single droplet evaporation characteristics. The influences of inlet temperature and residence time on the evaporation efficiency were also discussed. Differences between the two wastewater treatment technologies were analyzed. The results show that after being exposed to the hot flue gas, desulfurization wastewater droplets would rapidly lose their free water, form shells and turn into semi-dried particles, with temperature in the main evaporation zone of the dryer decreasing significantly. Increasing inlet temperature helps to improve the evaporation rate and reduce the moisture content of the outlet ash particles. By increasing the size of the dryers and controlling the amount of extracted flue gas, the residence time of high temperature flue gas in dryers can be extended, which is about to improve the heat utilization and achieve the drying effect with low gas-liquid ratio. In comparison with the bypass flue evaporation technique, centrifugal spray evaporation tower was better due to better atomization performance and uniform gas-liquid mixing.