Selective concentration treatment of circulating cooling water in thermal power plants based on nanofiltration technology
Promoting quality-based and gradient water usage and near-zero wastewater discharge is an important development content in the current green transformation stage of the thermal power industry.The circulating cooling water of thermal power plants has become a bottleneck due to its large volume but insufficient recycling and reuse.In this study,based on the characteristics of circulating cooling water quality,the concentration treatment of cooling water was proposed based on nanofiltration technology,the selective separation of mono-/di-valent ions was carried out,the concentrated water rich in Ca2+and Mg2+was used for auxiliary flue gas desulfurization,and the clean water was returned to the circulating cooling section,aiming at controlling the scaling problems of cooling towers and improving the overall utilization rate of water resources in thermal power plants.In this study,the mass concentration characteristics of five commercial nanofiltration membranes(NF245,NF270,DF30,DF90 and XCN)were compared.The XCN membrane was selected and used for nanofiltration separation treatment of practical circulating cooling water,which could achieve high rejection of Ca2+and Mg2+greater than 97％,while the rejection rate of Na+was stable at 20％.At 10％water recovery,the ion selectivity of SNa/Mg and SNa/Ca could reach up to 36.7 and 30.5,showing good application potential.
thermal power plantcirculating cooling waternanofiltration membraneselective separationwastewater reclamation
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