脱硫废水烟气蒸发过程中氯离子气固相分配模型及实验研究

随着国家"水污染防治行动计划"政策的提出,脱硫废水零排放已成为电厂水污染深度治理的新趋势。针对高温烟气蒸发脱硫废水技术应用中面临的核心技术问题,即不同工况条件下氯离子气相转化特性问题开展模型及实验研究。将经典的气液相平衡理论应用于复杂的脱硫废水混盐体系,基于状态方程法计算得出理想体系中以温度为自变量的氯离子气固相分配系数模型。之后,将得出的理想模型用复杂体系废水即脱硫废水进行验证和线性修正,引入修正系数ε和修正常数φ。利用自行设计的实验台开展实验研究,分析各个影响因素对氯离子气固相分配的显著性,影响最大的因素为温度,其次是pH和氯离子浓度,脱硫废水中所含的主要阳离子影响最大的是Mg~(2+),其次是Ca~(2+)和Na~+。得出的实际废水和正交实验数据用以拟合数据,确定了修正系数ε=1.068,修正常数φ中包含了上述影响氯离子气相转化的关键环境参数和水质参数。以MATLAB为计算工具对数据进行拟合,选取指数、对数及线性函数3种拟合形式,其中线性拟合的相关性最高,拟合度R~2为0.925 8,达到拟合要求。得到了适用于180～380℃的氯离子气固相分配系数模型。研究结果为脱硫废水烟气蒸发技术的应用提供了关键数据,实现了对脱硫废水蒸发过程中氯离子挥发量的量化及预测,可为该技术的工程实践提供参考。

Model and experimental research on gas solid phase partition of chloride ion in the process of desulfurization wastewater evaporation using flue gas

Since the promulgation of “water pollution control action plan” in China,a zero liquid discharge of desulfurization wastewater has become a new trend of water pollution control in power plant.Aiming at the core technical issue on the application of desulfurization wastewater evaporation technology using high temperature flue gas,the modeling and experimental research on the gas phase conversion characteristics of chloride ion under different operation conditions were carried out in this paper.The traditional gas liquid equilibrium theory was applied to the complex mixed salt system.Based on state equation,the model of chloride ion gas solid phase partition coefficient in ideal system was calculated.The ideal model was validated and linearly corrected with complex water namely desulfurization wastewater by correction factor ε and correction constant φ.Then,experimental research was conducted using self designed device.The interaction and significance of each factor were compared and analyzed.The order of influence significance on chloride ion gas solid distribution coefficient is temperature＞pH＞Cl- concentration＞Mg2+ concentration＞Ca2+ concentration＞Na+ concentration.The correction factor is determined using real desulfurization wastewater and orthogonal experimental data ε= 1.068.The correction constant φ contains key environmental parameter like temperature and water quality parameters that affect the gas phase conversion of chloride ion.MATLAB was used to calculate the models,three fitting forms were selected and the linear fitting had the highest correlation R2=0.925 8 that meets with requirement.Finally,the model of chlorine ion gas solid phase partition coefficient suitable for the temperature range from 180 to 380 ℃ was obtained.The study provides key data for the application of high temperature flue gas evaporation technology,obtains the quantification and prediction of chloride ion volatilization during desulfurization wastewater evaporation.The research results provide an important theoretical and practical reference for the application of this technology.