脱硫废水蒸发浓缩过程中的沸点研究  

Study on the boiling point variation during the evaporation and concentration process of desulfurization waste water

作　　者：张野虎 董文伟[1] 魏星 ZHANG Yehu;DONG Wenwei;WEI Xing(Jiangsu Xinhai Power Plant Co.,Ltd.,Lianyungang 222000,Jiangsu China;Chengdu Raise Environmental Technology Co.,Ltd.,Chengdu 610000,Sichuan China)

机构地区：[1]江苏新海发电有限公司,江苏连云港222000 [2]成都锐思环保技术股份有限公司,四川成都610000

出　　处：《电力科技与环保》2024年第6期669-676,共8页Electric Power Technology and Environmental Protection

基　　金：国家自然科学基金项目(51602228)。

摘　　要：为给燃煤电厂脱硫废水蒸发浓缩工艺系统中浓缩塔浆液的排出时机和排出量的调控提供指导。本文采用4种主要溶液(MgCl_(2)、MgSO_(4)、NaCl、Na_(2)SO_(4))试验模拟脱硫废水蒸发浓缩过程,研究蒸发浓缩过程中离子浓度与沸点升高之间的相关性。结果表明,不同盐类溶液在相同浓度下沸点上升顺序依次为MgCl_(2)、NaCl、MgSO_(4)和Na_(2)SO_(4),MgSO_(4)和Na_(2)SO_(4)在浓度达到0.4 mol/100gH_(2)O和0.3 mol/100 gH_(2)O左右时结晶析出,MgCl_(2)难以结晶析出;当NaCl达到饱和浓度后,溶液沸点的上升取决于MgCl_(2)浓度,溶液沸点可达76℃以上;晶种的加入降低了结晶的起始温度,蒸发结晶后期,溶液中主要为高溶解度的MgCl_(2),当溶液密度达到1.3~1.4 g/mL后,停止蒸发浓缩并冷却至常温,可析出大量晶体,可避免过多热量消耗;为维持浓缩塔的稳定运行,浆液的饱和温度在64.5~68.5℃之间,浆液的饱和蒸气压保持在18~20 kPa之间,在废水浓缩结晶后期提高固液分离效果,有利于提升泥饼的质量和滤液的循环再利用效率。In order to provide guidance for the regulation of the discharge timing and discharge volume of the thickener slurry in the desulfurization wastewater evaporation and concentration process system of a coal-fired power plant. In this paper, four main solutions(MgCl_(2), MgSO_(4), NaCl, Na_(2)SO_(4)) were used to simulate the evaporation and concentration process of desulfurization wastewater, and the dependence between the ion concentration and the boiling point elevation during the evaporation and concentration process was studied. The results showed that the boiling points of different salt solutions at the same concentration rose in the order of MgCl_(2), NaCl, MgSO_(4) and Na_(2)SO_(4), MgSO_(4) and Na_(2)SO_(4) crystallized when the concentration reached about 0.4 mol/100 gH_(2)O and 0.3 mol/100 gH_(2)O, and it was difficult for MgCl_(2) to crystallize and precipitate. When NaCl reached saturation concentration, the rise of the boiling point of the solution depended on the MgCl_(2) concentration, and the boiling point of the solution could be up to 76 ℃ or more. The addition of crystal species reduced the starting temperature of crystallization, evaporation and crystallization of the late stage, the solution is mainly high solubility of MgCl_(2). When the solution density reached 1.3~1.4 g/mL, stop evaporation and concentration and cooling to room temperature, a large number of crystals could be precipitated, and excessive heat consumption can be avoided. In order to maintain the stable operation of the concentration tower, the saturation temperature of the slurry was between 64.5~68.5 ℃, and the saturation vapor pressure of the slurry was kept between 18~20 k Pa, which improved the solid-liquid separation effect in the late stage of wastewater concentration and crystallization, and was conducive to the improvement of the quality of the mudcake and filtrate recycling and reuse efficiency.

关 键 词：脱硫废水 烟气余热 蒸发-浓缩-结晶 沸点升 废水零排发 

分 类 号：TK09[动力工程及工程热物理]