低温三效蒸发工艺中脱硫废水蒸发特性研究

Evaporation characteristics of desulfurization wastewater in low-temperature three effect evaporation process

脱硫废水蒸发特性是低温三效蒸发工艺参数确定的重要指标,通过蒸发实验,研究了脱硫废水蒸发速率与废水悬浮固、含盐浓度、密度间的关系,确定了系统最佳运行状态下的出料浓度。实验结果表明:脱硫废水悬浮固低利于废水蒸发,废水中固体颗粒可为盐分结晶提供晶种,颗粒冲刷作用降低了列管结垢风险,综合考虑蒸发效率和降低列管结垢风险,进水悬浮固建议为4%;脱硫废水蒸发速率随着含盐浓度的增加而降低,且含盐浓度越大蒸发速率降低得越快,可能与溶液黏度、溶液表面张力以及离子水合数有关;脱硫废水蒸发速率与溶液密度负相关,当溶液密度超过1400 kg/m^(3)时,蒸发速率显著下降,能耗明显增加,综合考虑系统高效运行和压滤机压滤效果,建议出料密度为1400 kg/m^(3)。浓缩倍率是低温三效蒸发系统工艺设计的重要指标,浓缩倍率与原水悬浮固负相关,应根据原水悬浮固及出料密度确定浓缩倍率进而完成三效蒸发系统总体设计。

The evaporation characteristic of desulfurization wastewater is an important indicator for determining the process parameters of three effect evaporation.Through evaporation experiments,the relationship between the evapo⁃ration rate of desulfurization wastewater and the solid content,salt content and density of wastewater was studied,and the discharge concentration under the optimal operation state of the system was determined.The experimental results showed that low solid content of desulfurization wastewater was conducive to wastewater evaporation,solid particles in the wastewater could provide crystal seeds for salt crystallization,particle scouring reduces the risk of tube scaling,considering evaporation efficiency and reducing the risk of tube scaling,the recommended solid con⁃tent of influent water was 4%.The evaporation rate of desulfurization wastewater decreases with the increase of salt concentration.Moreover,the higher the salt concentration was,the faster the evaporation rate decreased,which may be related to solution viscosity,solution surface tension and ion hydration number.The evaporation rate of desulfur⁃ization wastewater is negatively related to the solution density.When the solution density exceeded 1400 kg/m^(3),the evaporation rate decreased significantly and the energy consumption increased significantly.Considering the effi⁃cient operation of the system and the filter press effect,it recommended 1400 kg/m^(3) of the discharge density.The concentration ratio was an important indicator of the process design of the low-temperature three effect evaporation system.The concentration ratio was negatively related to the solid content of raw water.The concentration ratio should be determined according to the solid content of raw water and the discharge density to complete the overall design of the three-effect evaporation system.