煤化工行业正渗透膜浓缩零排放技术的应用

Application of forward osmosis MBC zero discharge technology in coal chemical industry

介绍了正渗透膜浓缩(MBC)工艺在煤化工厂综合排放废水回用工程中的应用。工程运行结果表明:MBC系统可将TDS为54000 mg/L的高压反渗透浓盐水浓缩至240000 mg/L,经蒸发结晶系统制备出含固率>80%的结晶盐。MBC的产水回收率可达到75%,TDS为11200 mg/L。MBC系统产水经两级反渗透脱盐后,TDS低于100 mg/L,脱盐后的产水可回用至循环水系统,从而实现煤化工废水的零排放。MBC的吨水蒸汽耗量仅为158 kg,远低于四效蒸发器,具有较低的运行能耗。采用氨水和二氧化碳作为汲取液,通过氨回收塔回收循环再利用,可节约药剂使用量。运行数据表明,以正渗透技术为核心的MBC工艺能够替代传统的四效蒸发器,保障零排放系统的稳定运行,在达到煤化工综合废水零排放的同时,极大地节约零排放处理过程中的能耗,可为煤化工企业带来良好的社会效益和经济效益。

The application of forward osmosis membrane concentration(MBC)process in the comprehensive dis⁃charge wastewater reuse project of coal chemical plant was introduced.The project operation results showed that the MBC system could concentrate high-pressure reverse osmosis concentrated brine with TDS of 54000 mg/L to 240000 mg/L,and prepare crystalline salt with solids content>80%by evaporation and crystallization system.The recovery rate of produced water from MBC could reach 75%with TDS of 11200 mg/L.The produced water of MBC system could be desalinated by two-stage reverse osmosis with TDS lower than 100 mg/L.The desalinated produced water could be reused to circulating water system,thus realizing zero discharge of coal chemical wastewater.The steam consumption of the MBC was only 158 kg/t,which was much lower than that of the four-effect evaporator and had lower energy consumption.Ammonia and carbon dioxide were used as the extraction solution and recycled through the ammonia recovery tower,which could save the amount of chemicals.The operation data showed that the MBC process with forward osmosis technology as the core could replace the traditional four-effect evaporator and guarantee the stable operation of the zero-discharge system,which could bring good social and economic benefits to the coal chemical enterprises by greatly saving the energy consumption in zero discharge process while achieving zero discharge of comprehensive wastewater.