Experimental study and mechanism analysis of softening and magnesium recovery of high magnesium desulfurization wastewater

doi:10.16085/j.issn.1000-6613.2019-0504

Abstract

Abstract: With the promulgation of a series of water and wastewater policies and regulations including the Energy Conservation Law and the Environmental Protection Law, domestic pollution and wastewater discharge standards have been more stringent, which undoubtedly makes the desulfurization wastewater deep processing research enthusiastic. Further heating, and softening of wastewater is particularly important as an essential part of the advanced treatment of wastewater. Based on the water quality characteristics of the desulfurization wastewater from the effluent from the triple tank of a thermal power plant in China, a softening method for the desulfurization wastewater is introduced. The process of treating the wastewater in the triple tank is appropriately modified, and the lye is added to the desulfurization wastewater. Experiments with wastewater softening and magnesium recovery were carried out by carbonization. The experimental results show that it is reasonable to adjust the pH value of the desulfurization wastewater to 8.8, 10.2 and 8.5 except for the heavy metal stage, the recovery of magnesium hydroxide stage and the carbonization stage. The treated desulfurization wastewater can meet the requirements of the subsequent water treatment unit. Maximum recovery of high quality magnesium hydroxide products.

Key words: desulfurization wastewater, softening, heavy metals removal, recovering calcium and magnesium, economic evaluation

摘要： 随着《节约能源法》、《环境保护法》等一系列用水排水政策和法规的颁布，国内对污水、废水排放标准有了更严格的规定，这无疑使得脱硫废水深度处理研究热情进一步升温，而对废水的软化处理作为废水深度处理的一个必要环节就显得尤为重要。本文根据国内某火力发电厂三联箱前出水的脱硫废水水质特征，介绍了一种脱硫废水的软化方法，在三联箱处理废水的工艺基础上做了适当的改造，通过向脱硫废水加入碱液和碳化的方法介绍了废水软化和镁回收的实验。实验结果表明，去除重金属阶段、回收氢氧化镁阶段和碳化阶段分别将脱硫废水的pH调至8.8、10.2和8.5是比较合理的，处理后的脱硫废水既可以达到后续水处理单元的要求又可以最大程度的回收高品质的氢氧化镁。

关键词: 脱硫废水, 软化, 重金属去除, 回收钙镁, 经济评估

CLC Number:

X703

WANG Xingjun, ZHOU Yongchun, AN Dexin, WU Wei, LIU Yazheng, LIN Chenyu, MA Shuangchen. Experimental study and mechanism analysis of softening and magnesium recovery of high magnesium desulfurization wastewater[J]. Chemical Industry and Engineering Progress, 2019, 38(s1): 252-258.

王兴俊, 周永春, 安德欣, 吴伟, 刘亚争, 林宸雨, 马双忱. 高镁脱硫废水软化和镁回收实验与机理分析[J]. 化工进展, 2019, 38(s1): 252-258.

References

[1] 黄群亮. 湿法烟气脱硫改造工艺的优选及经济性评价[D]. 广州:华南理工大学, 2015. HUANG Qunliang. Optimization and economic evaluation of wet flue gas desulfurization reforming process[D]. Guangzhou:South China University of Technology, 2015.
[2] 张彬彬. 火电机组烟气脱硫系统的节能优化运行[J]. 工程技术(文摘版), 2017, 6(4):256. ZHANG Binbin. Energy-saving optimization operation of flue gas desulfurization system for thermal power unit[J]. Engineering Technology (Abstract), 2017, 6(4):256.
[3] 中华人民共和国环境保护部. 国务院关于印发水污染防治行动计划的通知[EB/OL].[2015-07-26]. http://zfs.mep.gov.cn/fg/gwyw/201504/t20150416_299146.htm. Ministry of Environmental Protection of the People's Republic of China. Notice of the ministry of environmental protection of the People's Republic of China and the state council on printing and discharging the water pollution prevention and control action plan[EB/OL].[2015-07-26]. http://zfs.mep.gov.cn/fg/Gwyw/201504/t20150416_299146.htm.
[4] 中华人民共和国环境保护部. 火电厂污染防治最佳可行技术指南(发布稿)[EB/OL].[2017-05-21]. http://kjs.mep.gov.cn/hjbhbz/bzwb/wrfzjszc/201706/W020170609556701647383.pdf. Ministry of Environmental Protection of the People's Republic of China. Best available technical guidelines for pollution prevention and control of thermal power plants (release)[EB/OL].[2017-05-21]. http://kjs.mep.gov.cn/hjbhbz/bzwb/Wrfzjszc/201706/W020170609556701647383.pdf.
[5] 李兴华, 金万元, 张劲松, 等. 湿法脱硫吸收塔浆液起泡的影响因素[J]. 热力发电, 2015(8):121-124. LI Xinghua, JIN Wanyuan, ZHANG Jinsong, et al. Factors affecting the foaming of slurry in wet desulfurization absorption tower[J]. Thermal Power Generation, 2015(8):121-124.
[6] 刘秋生. 烟气脱硫废水"零排放"技术应用[J]. 热力发电, 2014, 43(12):114-117. LIU Qiusheng. Application of "zero emission" technology for flue gas desulfurization wastewater[J]. Thermal Power Generation, 2014, 43(12):114-117.
[7] 朱思洁. 高盐水回用对脱硫系统影响及其控制[D]. 保定:华北电力大学, 2018. ZHU Sijie. Effect of high salt water reuse on desulfurization system and its control[D]. Baoding:North China Electric Power University, 2018.
[8] 柳杨, 刘德志. 脱硫废水深度处理方法[J]. 电站系统工程, 2007, 23(3):49-50. LIU Yang, LIU Dezhi. Advanced treatment method of desulfurization wastewater[J]. Power System Engineering, 2007, 23(3):49-50.
[9] 张志杰, 王建华, 易庚, 等. 燃煤电厂脱硫废水烟气蒸发特性的流场模拟[J]. 中国煤炭学报, 2015, 40(3):678-683. ZHANG Zhijie, WANG Jianhua, YI Geng, et al. Flow field simulation of flue gas evaporation characteristics of desulfurization wastewater from coal-fired power plants[J]. China Journal of Coal Science, 2015, 40(3):678-683.
[10] 叶春松, 罗珊, 张弦, 等. 燃煤电厂脱硫废水零排放处理工艺[J]. 热力发电, 2016, 45(9):105-108, 139. YE Chunsong, LUO Shan, ZHANG Xian, et al. Zero emission treatment process for desulfurization wastewater from coal-fired power plants[J]. Thermal Power Generation, 2016, 45(9):105-108, 139.
[11] 王可辉, 蒋芬, 徐志清, 等. 燃煤电厂脱硫废水零排放工艺路线研究[J]. 工业用水与废水, 2016, 47(1):9-12. WANG Kehui, JIANG Fen, XU Zhiqing, et al. Study on zero emission process route of desulfurization wastewater in coal-fired power plants[J]. Industrial Water & Wastewater, 2016, 47(1):9-12.
[12] 史德佩, 周然. 略论燃煤电厂脱硫废水零排放处理与预处理的软化技术[J]. 山东工业技术, 2018(21):88. SHI Depei, ZHOU Ran. A brief discussion on softening technology for zero discharge treatment and pretreatment of desulfurization wastewater from coal-fired power plants[J]. Shandong Industrial Technology, 2018(21):88.
[13] 叶春松, 黄建伟, 刘通, 等. 燃煤电厂烟气脱硫废水处理方法与技术进展[J]. 环境工程, 2017, 35(11):10-13. YE Chunsong, HUANG Jianwei, LIU Tong, et al. Progress in treatment methods and technology of flue gas desulfurization wastewater in coal-fired power plants[J]. Environmental Engineering, 2017, 35(11):10-13.
[14] 周汛. 燃煤电厂脱硫废水污泥的处置与综合利用[J]. 现代经济信息, 2016(20):359. ZHOU Xun. Disposal and comprehensive utilization of desulfurization wastewater sludge in coal-fired power plants[J]. Modern Economic Information, 2016(20):359.
[15] 郑荣光, 王芳. 氢氧化镁处理含铅废水的研究[J]. 无机盐工业, 2000, 32(l):26-27. ZHENG Rongguang, WANG Fang. Study on treatment of lead-containing wastewater by magnesium hydroxide[J]. Inorganic Salt Industry, 2000, 32(l):26-27.
[16] 刘明. 卤水制备阻燃级氢氧化镁新工艺研究[D]. 北京:北京化工大学, 2016. LIU Ming. Study on new process for preparation of flame retardant magnesium hydroxide from brine[D]. Beijing:Beijing University of Chemical Technology, 2016.
[17] 陈美琴, 吴志平, 胡云楚. 氢氧化镁协同阻燃剂的研究进展[J]. 应用化工, 2008, 37(8):939-942. CHEN Meiqin, WU Zhiping, HU Yunchu. Research progress of synergistic flame retardant of magnesium hydroxide[J]. Applied Chemical Industry, 2008, 37(8):939-942.
[18] 梁恩泉. 不同阻燃剂对麦秸纤维/回收聚丙烯复合材料性能的影响[D]. 南京:南京航空航天大学, 2010. LIANG Enquan. Effect of different flame retardants on the properties of wheat straw fiber/recycled polypropylene composites[D]. Nanjing:Nanjing University of Aeronautics and Astronautics, 2010.
[19] 华东科技大学化学系, 四川大学化学工程学院. 分析化学[M]. 北京:高等教育出版社, 2003:425. Department of Chemistry, East China University of Science and Technology; School of Chemical Engineering, Sichuan University. Analytical chemistry[M]. Beijing:Higher Education Press, 2003:425.
[20] 张春桃, 王鑫, 王海蓉, 等. 燃煤电厂脱硫废水的零排放处理技术[J]. 化工环保, 2016(1):30-35. ZHANG Chuntao, WANG Xin, WANG Hairong, et al. Zero emission treatment technology for desulfurization wastewater from coal-fired power plants[J]. Chemical Industry, 2016(1):30-35.
[21] 刘美淋. 基于苦卤资源的一维纳米氢氧化镁阻燃剂合成工艺研究[D]. 青岛:山东科技大学, 2007. LIU Meilin. Synthesis of one-dimensional nanometer magnesium hydroxide flame retardant based on bitter brine resources[D]. Qingao:Shandong University of Science and Technology, 2007.
[22] KUMARI L, LI W Z, VANNOY C H, et al. Synthesis, characterization and optical properties of Mg(OH)₂ micro-/nanostructure and its conversion to MgO[J]. Ceramics International, 2009, 35(8):3355-3364.
[23] 刘志强, 李小斌. 湿化学法制备超细粉末过程中的团聚机理及消除方法[J]. 化学通报, 1999(7):54-57. LIU Zhiqiang, LI Xiaobin. Agglomeration mechanism and elimination method in preparation of ultrafine powder by wet chemical method[J]. Chemistry, 1999(7):54-57.
[24] 黄浪欢, 曾令可, 罗民华. 湿化学方法制备纳米粉体时闭聚现象的探讨[J]. 佛山陶瓷, 2001(10):11-13. HUANG Langhuan, ZENG Lingke, LUO Minhua. Discussion on the phenomenon of closed polymerization when preparing nano-powder by wet chemical method[J]. Foshan Ceramics, 2001(10):11-13.