沿海火电厂大型膜法海水淡化系统设计及运行分析

Design and operation analysis of large-scale membrane seawater desalination system in coastal thermal power plant

为保障城市用水安全,某沿海城市依托当地电厂建设规模为30 000 m^(3)/d的海水淡化工程,采用“V型滤池+超滤+海水反渗透+淡水反渗透”全膜法工艺,系统产水最终纳入市政管网。运行结果表明,夏季运行时,淡水反渗透与海水反渗透产水按照1∶2的体积比掺混保证了产水水质的稳定,处理后产水水质满足《生活饮用水卫生标准》(GB 5749—2006),且硼质量浓度满足<1 mg/L的要求。采用电解海水淡化后的浓盐水制氯并用于原水杀菌,可减少浓盐水处理费用和药剂费用,降低系统运行成本。本系统工艺流程简单,吨水投资费用约8 000元,吨水运行成本约4.2元,吨水处理能耗约4 kW·h,具有较好的社会效益和经济效益。

To ensure urban water safety,a coastal city built a seawater desalination project with a scale of 30 000m^(3)/d relying on a local power plant,using the full membrane method process including V-type filter,ultrafiltration,seawater reverse osmosis and freshwater reverse osmosis.The water produced by the system was finally incorporated into the municipal pipe network.The operation results showed that during summer operation,the produced water quality was guaranteed to be stable by mixing freshwater reverse osmosis and seawater reverse osmosis product water in a volume ratio of 1∶2.After treatment,the water quality of the produced water met the Standards for Drinking Water Quality(GB 5749—2006),and met the requirement of boron mass concentration<1 mg/L.The concentrated brine after seawater desalination was used for electrolytic chlorination for raw water sterilization,which could reduce the cost of concentrated brine treatment,reagent and the system operation.The process flow of this system was simple,with an investment cost of about 8 000 yuan per ton of water,an operating cost of about 4.2 yuan per ton of water,and an energy consumption of about 4 kW·h per ton of water.It had good social and economic benefits.