RCM Application for Availability Improvement of Gas Turbines Used in Combined Cycle Power Stations

This paper presents a reliability-based method aiming to improve the availability of gas turbine installed in combined-cycle thermoelectric power plant. The importance of the gas turbine is related with the power plant operational principle. The gas turbine transforms the chemical energy generated by combustion in mechanical energy to rotate the generator´s shaft. The exhaust gas is used to heat water in the steam generator, which is part of the steam cycle. The failure of the gas turbine causes the power plant unavailability. The method presented is based on the Reliability Centered Maintenance (RCM) concepts. The method first step requires the development of the Failure Mode and Effects Analysis (FMEA) of the turbine components to define the most critical items for turbine operation. This criticality is based on the evaluation of the component failure effect on the turbine operation. Once the critical items are defined a maintenance policy can be proposed for those components, considering the Reliability Centered Maintenance (RCM) concepts, aiming to improve the equipment availability. The reliability of the turbine is calculated based on the failure data records. Considering the time to repair data and the preventive maintenance tasks associated with the equipment, the gas turbine availability is evaluated. The analysis not only allows the evaluation of the actual maintenance policy but also allows the prediction of possible availability improvement taking in view the application of new maintenance procedures, based on RCM concepts.