燃煤电厂脱硫废水全浓缩过程析盐规律的模型化

Modeling Salt Precipitation Behaviors in the Whole Concentration Process of Desulfurization Wastewater from Coal-fired Power Plant

燃煤电厂脱硫废水是成分复杂的体系,量化表达脱硫废水蒸发过程的析盐规律,是优化浓缩过程和设计分盐过程的基础。文章针对含有Na^(+)、Mg^(2+)、Ca^(2+)等阳离子和Cl^(-)、SO^(2-)_(4)等阴离子,固相组分涉及32种固体盐的石灰石膏法硫废水,开发了具有通用性的DswEp模型,进行全浓缩过程的析盐规律的量化表达。结果表明DswEp模型的量化计算结果与相图一致,与复杂体系实验过程数据吻合;获得了盐硝分离过程,氯化钠亚型和硫酸镁亚型脱硫废水全浓缩过程的液相密度、沸点升、比热等物性数据随蒸发进程的变化;获得了氯化钠亚型废水4个析盐阶段、硫酸镁亚型5个阶段的准确划分和析盐量的精确表达。研究结果为燃煤电厂废水的零排放和资源化过程设计提供了依据。

Desulfurization wastewater from coal-fired power plant is a system with complex components.Quantitative expression of salt precipitation behaviors in the evaporation process of desulfurization wastewater by lime gypsum method is the basis for optimizing the concentration process and designing the salt separation process.In this article,a universal DswEp model is developed for the lime gypsum process sulfur wastewater containing cations such as Na^(+),Mg^(2+),Ca^(2+),anions such as Cl^(-),SO^(2-)_(4),and solid components involving 32 species of solid salts,to quantitatively express the salt precipitation behaviors in the whole concentration process.The results showed that the quantitative calculation results of DswEp model are consistent with the phase diagram and the experimental process data of complex systems,and the changes of liquid phase density,boiling point rising and heat capacities in the whole concentration process of desulfurization wastewater with the evaporation process are obtained;The accurate division of four salt precipitation stages of sodium chloride subtype wastewater and five stages of magnesium sulfate subtype wastewater and the accurate expression of salt precipitation amount were obtained.The results provides a basis for the zero discharge and resource process design of wastewater in coal-fired power plant.