电渗析技术处理LNG工厂循环冷却系统排污水研究

Treatment of waste water from recirculating cooling system in LNG plant using electrodialysis technology

关键词:  电渗析  LNG  废水  循环冷却水 

Key words:  electrodialysis  LNG  waste water  recirculating cooling water

摘要:

湖北LNG工厂循环冷却水系统每日排污量高达1 200 m³,直接排放不仅造成水资源的浪费,同时对下游污水处理厂的运行产生较大冲击。为提高该部分废水的重复利用率,设计采用“多级连续式电渗析除盐系统”对其进行脱盐处理后回用于循环水系统。经计算,50 m³/h的电渗析装置设计流速采用V=5.0 cm/s,设计总脱盐率ε=75%~80%,产水电导率300~350 μs/cm。装置建成后调试结果表明,最佳操作电压为110 V,最适宜进水流量为50 m³/h,产水各项指标满足预期设计要求。每年可减少新鲜水消耗和废水排放各30×10⁴ t,产生直接经济效益约60万元。 

Abstract:

waste water from recirculating cooling system in Hubei LNG plant amounts up to 1 200 m³ per day. Direct discharge would not only cause the waste of water resource, but also bring large impact to the operation of the downstream sewage treatment plants. In order to promote the recycling rate, a “multi-stage continuous electrodialysis desalination system” was designed to treat the waste water for reusing. According to the design calculation, the flow velocity, the overall desalination rate, the conductivity of the treated water were set at 5.0 cm/s, 75%~80%, and 300~350 μs/cm respectively in 50 m³/h electrodialysis system. The debugging results showed that the optimum operating voltage was 110 V, the most suitable flow rate was 50 m³/h, and the treated water from the electrodialysis system could meet all the design requirements. The process can reduce the fresh water consumption and waste water discharge by 300 000 tons per year respectively, and bring direct economic benefit of about RMB 600 000 yuan each year.