Copper Deposition in Stator Cooling Water Systems

Water cooled steam turbine-generator stator systems are subject to flow restrictions and pluggage by copper that originates from within the stators. Deposition may occur within hollow stator bars or coils, or in filters or screens in the water flow circuit. In extreme cases of deposition, flow restriction can cause the generator to overheat due to reduction of cooling flow, resulting in unit outages and potentially serious equipment damage. Chemistry programs to minimize corrosion and transport of copper within the system include high oxygen, low oxygen, and alkaline (pH elevation). In all cases high purity water is required for the application. Examination of copper deposits can provide clues to the adequacy of the chemistry treatment program for minimizing system corrosion.