常温喷雾蒸发处理含盐水蒸发特性研究

Study on evaporation characteristics of brine in spray evaporation process at ambient temperature

我国鼓励工业废水"近零排放",含盐水的深度处理备受关注,电厂脱硫废水、矿山废水治理等工业废水可采用常温机械喷雾蒸发技术处理。自建室外常温喷雾蒸发试验台,测量含盐水蒸发速率并对蒸发产物进行扫描电子显微镜(SEM)表征。研究发现,雾化颗粒越细,蒸发速率越快,当颗粒粒径为500μm以上时,降低颗粒粒径对蒸发速率提高影响较小;含盐量越低,蒸发速率越大,但差别较小;喷雾蒸发速率与风速近似呈线性正相关、与温度近似呈指数型正相关、与湿度近似呈线性负相关;大风气象时,风速是影响喷雾蒸发速率的决定因素;温度<15℃时,温度是限制喷雾蒸发速率的主要因素;湿度>90%时,湿度是限制喷雾蒸发速率的主要因素;试验中机械雾化蒸发速率是自然蒸发速率的4~12倍;同时注意到机械雾化蒸发存在风吹损失问题,需要采取措施避免高含盐水带来二次污染。

China encourages"nearly zero discharge"of industrial wastewater,and advanced treatment of brine is of great deep concern. Desulfurization wastewater,mining wastewater and other industrial wastewater can be processed by spray evaporation technologyat ambient temperature. On the self-built outdoor test beds for spray evaporation test,the evaporation rate of brine was measured and the characteristics of evaporation products were described by scanning electron microscope(SEM). Smaller atomized particulars lead to a larger evaporation rate. When the particle diameter is over 500 μm,decreasing the size of particular has small effect on evaporation rate. Smaller salinity leads to a larger evaporation rate,but the difference is slight. The spray evaporation rate has an approximately linear positive correlation with the wind velocity,exponential positive correlation with temperature,and a negative correlation with the relative humidity.The wind velocity is the decisive factor of the spray evaporation rate as wind velocity is large. When the relative humidity is over90%,humidity is the decisive factor. When the temperature is less than 15 ℃,the temperature is the main factor. The mechanical atomization rate of the test is about 4 ～ 12 times of natural evaporation rate. At the same time,it is noted that there is wind loss in spray evaporation rate,and measures should be taken to avoid the secondary pollution caused by water of high salinity.