Failure Mechanisms Encountered by Rotating Equipment in Geothermal Steam Service

Abstract

Geothermal rotors operate at low pressure and temperatures and are constructed of hardware (rotors and diaphragms) derived from equipment used in the nuclear power plants. The operating conditions are aggressive when compared to the steam chemistry prevalent in the closed systems of conventional power plants. This paper will review the typical steam path damage mechanism encountered during normal geothermal steam turbine service and identify remediation methods if any that are available to recover and continue to operate the capital equipment. Topics reviewed will be: Foreign and Domestic Object damage, Scale Formation, Erosion Mechanisms, Rubbing, Fretting Corrosion, Vibratory Stresses, Pitting Corrosion and Sulfide Stress Cracking.