燃煤电厂脱硫废水热法零排放系统设计及分析  

Design and analysis of thermal zero discharge for flue gas desulfurization wastewater of coal-fired power plants

作　　者：安雪峰 刘广建[1] 陈海平[1] AN Xuefeng;LIU Guangjian;CHEN Haiping(School of Energy Power and Mechanical Engineering,North China Electric Power University,Beijing102206,China)

机构地区：[1]华北电力大学能源动力与机械工程学院,北京102206

出　　处：《洁净煤技术》2022年第6期175-183,共9页Clean Coal Technology

基　　金：国家重点研发计划资助项目(2018YFB0604301)。

摘　　要：随着我国环保政策的不断完善和水资源的严重缺乏,脱硫废水的深度处理及废水中水分回收具有重要意义。通过构建脱硫废水热法零排放全流程系统,提出3种热法浓缩工艺:多效蒸发系统(MEE)、单级机械蒸汽再压缩系统(MVR-S)和耦合MVR的多效蒸发系统(MEE-MVR),其中,MEE包括生蒸汽驱动的多效蒸发系统和低温烟气驱动的多效蒸发系统。以600 MW超临界机组为例,利用Aspen Plus软件进行流程模拟和系统经济性计算。计算结果表明:相对于传统的以生蒸汽为热源的多效蒸发系统,当采用低温烟气作为蒸发系统热源,则烟气降温5.5℃,如果忽略低温烟气成本,则具有较低的吨废水处理成本最低;单级MVR系统由于利用热泵蒸发技术,能耗大幅下降,但投资成本为传统多效蒸发系统的113%;耦合MVR的多效蒸发系统由于在较低浓度下蒸发了部分进料,因此其压缩机功耗相对单级MVR下降了30%,其吨废水处理成本约为传统多效蒸发系统的58.2%。With the continuous improvement of China′s environmental protection policies and the serious lack of water resources,the deep treatment of flue gas desulfurization(FGD)wastewater and water recovery are of great significance.In the present work,an overall zero liquid discharge(ZLD)process system for FGD wastewater was constructed,and three kinds of thermal concentration processes were pro⁃posed:multi-effect evaporation system(MEE),single stage mechanical vapor recompression system(MVR-S)and multi-effect evapora⁃tion system coupled with MVR(MEE-MVR).MEE includes multi-effect evaporation system driven by live steam and multi-effect evaporction system driven by low-temperature flue gas.Taking a 600 MW supercritical unit as an example,process simulation and system economics calculation were carried out using Aspen Plus software.The results show that compared with the traditional multi-effect evapora⁃tion system driven by live steam(MEE-S),the temperature of the flue gas is reduced by 5.5℃when the low-temperature flue gas is used as the heat source.If the cost of the low-temperature flue gas is ignored,the cost of wastewater treatment per ton is lowest.The energy con⁃sumption of single-stage MVR system is greatly reduced due to the use of heat pump evaporation technology,but the investment cost is 113%of MEE-S system.For the MEE-MVR system,the power consumption of the compressor is reduced by 30%compared with the MVR-S,and the cost of wastewater treatment per ton is about 58.2%of the MEE-S system.

关 键 词：脱硫废水 蒸发结晶 低能耗 零排放 机械蒸汽再压缩 

分 类 号：X703[环境科学与工程—环境工程]