混凝斜板沉淀池和V型滤池用于特大型海水淡化工程

Application of Coagulation Inclined Plate Sedimentation Tank and V-type Filter in Super-scale Seawater Desalination Project

国内某特大海水淡化项目一期工程(25×10^(4)m^(3)/d)预处理系统的混凝斜板沉淀池和V型滤池单个工艺单体规模分别为7.5×10^(4)m^(3)/d和2.5×10^(4)m^(3)/d。设计中采用了多级分布配水辅以水力学模拟流场分析的方法解决了大规模工艺单体因配水不均匀而影响运行效果的问题;同时针对海水盐分高、密度大、黏度高、藻类污染严重等特点,采用了具有二次强化接触絮凝作用、雷诺数(Re)小、不易积泥、沉淀效率更高的V型斜板沉淀设备和截污量大、抗污能力强、过滤周期长的大粒径均匀级配粗砂深床滤料滤池。实际运行稳定可靠,出水水质优良,在不同进水水质条件下混凝沉淀池出水浊度均稳定在5 NTU以下、V型滤池出水浊度≤0.1 NTU、V型滤池反冲洗周期为48 h,各项指标均优于设计要求。预处理系统投资约1.8亿元,单位运行成本为0.105元/m^(3)。

The scale of coagulation inclined plate sedimentation tank and V-type filter belonged to the pretreatment system of a super-scale seawater desalination phase I project(25×10^(4)m^(3)/d)is 7.5×10^(4)m^(3)/d and 2.5×10^(4)m^(3)/d,respectively.In the design,the method of multi-stage water distribution accompanied by hydraulic simulation flow field analysis was adopted to solve the problem of uneven water distribution affecting the operational performance of a single unit belonged to a large-scale process.In addition,in view of the characteristics of seawater with high salinity,high density,high viscosity and serious algae pollution,the project adopted the V-type inclined plate settling equipment with the advantages of secondary enhanced contact flocculation,small Reynolds number(Re),not easy to accumulate sludge and higher precipitation efficiency and the large particle size uniform graded coarse sand deep bed filter with large interception capacity,strong anti-fouling ability and long filtration period.The actual operation of the system was stable and reliable,and the efluent quality was excellent.Under different influent quality conditions,the efluent turbidity of coagulation sedimentation tank was always less than 5 NTU,the effluent turbidity of V-type filter was≤0.1 NTU,and the backwashing cycle of V-type filter was 48 h,and all the indicators were better than the design requirements.The investment of the pretreatment system was approximately 180 million yuan,and the operational cost was 0.105 yuan/m^(3).