Research And Application Of Urban Recycled Water In Circulating Cooling Water Of Power Plant

In thermal power plant, circulating cooling water accounts for70%～90%of total water amount. The supply water amount of consuming circulating cooling water reach to22000m3/din a thermal power plant of1000MW. Municipal sewage is becoming an important water resource that can be utilized because of its stability and dependability. However, the phenomenon of scale formation, corrosion and biological slime breeding will happen causing by higher alkalinity hardness, organics and dissolved salts in the reclaimed water, which affect the concentration ratio of circulating cooling water and safe operation of units work. Therefore, the reclaimed water demand advanced treatment. According to power plants engineering, the function mechanism and influence of advanced treatment water, NH3-N, sterilization and slime to antiscale, corrosion and protection of the condenser tube was researched in this study. Static and dynamic experiments were employed as demonstration test. Specific treatment process of reclaimed water included lime-coagulation, biological aerated filter (BAF) to decrease hardness, NH3-N and organic matter content respectively. The addition of acid and corrosion inhibitor was to adjust pH and improve the concentration ratio of circulating cooling water. Reclaimed water after advanced treatment can meet the water quality requirement of circulating cooling water in power plant, and can run stably on the higher concentration ratio, prevent a series of problems, such as corrosion, scaling, breeding of bacteria and algae. Appropriate drug and dose, controlling indicators of lime coagulation and technological process of BAF to treat reclaimed water were proposed in this paper. In addition, electrochemical corrosion, cyclic polarization and scanning electron microscope (SEM) were conducted to establish the corrosive influence of different equipments and materials. The study provided a scientific basis for the choice of generator condenser tube, management and maintenance. In view of the actual running of power station, we conducted dynamic simulation experiment of circulating water with three water distribution mode. The unit is running steadily without corrosion and scaling, heat exchange efficiency was also stable, which confirmed the practicality and reliability of the treatment process.