Anti-corrosion And Alkaline Treatment Of Cooling Water System Of Generator

As the economic and social development demands more and more power,the capacity of steam turbine in thermal power plants is increasing,and some units with small installed capacity are gradually replaced by millions of units.With the increase of turbine stand-alone capacity,the temperature of line load,wire rod and coil will increase,and the stator and rotor windings will generate a lot of heat in the operation of the unit,which must be taken away by the cooling medium.The cold water system in the generator is a very important auxiliary system of the turbine generator.Units#3 and#4 of Chaozhou Power Plant are two 1000MW ultra-supercritical units,and the internal cooling water system is water hydrogen hydrogen cooling.Through the weekly water vapor system identification experiment,it was found that the copper content of the cooling water in the two units was sometimes high,and the conductivity and p H value of the cooling water in the two units also exceeded the standard,which did not meet the water quality requirements of one million units.The current internal cooling water treatment mainly includes adding alkaline reagent to adjust the p H value of internal cooling water and combining with small mixing bed by bypass to adjust the water quality of internal cooling water,but the effect is not ideal.This paper summarizes the status quo and existing problems of internal cooling water system operation in large steam turbine units,analyzes the limitations of several internal cooling water quality regulation methods in the actual production process,and explores the feasibility of micro-alkaline treatment method in internal cooling water treatment.The static corrosion experiment of T₂copper was carried out.The analysis of the experimental results shows that when the temperature is in the range of 40?to 80?,the increase of temperature promotes the formation of copper surface oxide.When the temperature is in the range of the operating temperature of the generator,the increase of temperature is beneficial to the anti-corrosion of the inner cooling water system.When the p H is between 8.0 and 9.0,a protective Cu₂O film is formed on the surface of copper,which inhibits the corrosion of copper matrix.In this p H range,copper wire corrosion is favorable.When the dissolved oxygen content is in the range of0.06-0.1mg/L,the conductivity and copper ion content in the solution are small,within this range of dissolved oxygen content is beneficial to the corrosion resistance of copper wire.The results of static corrosion test provide basis for analyzing copper corrosion in different environments and anticorrosion measures for copper system.On the basis of the static corrosion experiment of T₂copper and the operating experience of other power plants,the simulation device for micro-alkaline treatment of inner cooling water system was studied.Dow resin was selected as the ideal resin for internal cooling water treatment through performance test.The ratio of Na type resin and H type resin is controlled as2:1.After the ion exchange column,the effluent conductivity can be controlled in the range of0.25?S/cm?1.08?S/cm,and the p H value can be controlled in the range of 7.8?8.5.At this time,the effluent water quality is the best,so the ratio of Na type resin and H type resin is 2:1.Through the dynamic simulation experiment,it can be seen that the p H value of the effluent increases,it can be increased from 6.30 to about 8.30 of raw water,the conductivity and copper ion content are reduced,the conductivity of simulated internal coolant water can be reduced from1.10?S/cm?2.43?S/cm to 0.98?S/cm?2.15?S/cm,and the copper ion content can be reduced from 101?g/L?213?g/L to 2.5?g/L?22.3?g/L,indicating that the micro-alkaline treatment device can make the inner cold water reach the micro-alkaline and remove impurity ions.In addition,a protective film is formed on the surface of the copper sheet effluent from the slightly alkaline device,which can inhibit the corrosion of the copper wire.It shows that the alkaline treatment device can effectively regulate the water quality of the cooling water and inhibit the corrosion of the copper wire of the generator.The study on the micro-alkaline treatment simulation device of the inner cooling water system provides a feasible scheme for the modification of ion exchanger equipped with the inner cooling water system of the generator in Chaozhou Power Plant.