Topics for On-Site Rehabilitation of a 30 MW Geothermal Turbine

During a major overhaul of a 30 MW geothermal turbine for the electricity sector of Mexico, a new rotor and new diaphragms were provided to recovery the power rate of the unit. Recuperation of the horizontal joint of upper and lower casings was required, as well as the inner diameter for diaphragm lodgings in both casings. The Geothermal steam turbines in Mexico suffer of accelerate degradation due mainly to high levels of sulphidric acid in the geothermal steam flow. Corrosion and dust particles are often present in the flow path turbine components affecting the performance and maintenance. In addition, the paper includes topics for on-site rehabilitation which include complex activities and challenges that must be taken into account for a successful rehabilitation process. The mapping process for horizontal joint casing, the processes used for recovery of planarity, the post weld heat treatments used for these components, and the machining process used for recovery inner diameters of casings.