Análise de dados de vida de atuadores eletro-hidráulicos das turbinas de uma central termoelétrica

Abstract

This work was conceived from the observation of an existing problem of variability in the useful life of the turbine’s electro-hydraulic positioner actuator of the ArcelorMittal Tubarão Power Plant. Thereby, from the methodologies studied in the present course, a possibility of both LDA and RCM studies was identified to determine the behavior of such positioners in terms of life span as well as to estimate its optimal useful life from the requirements of the process. The development of the work involves the methodology of identification of failure modes for this equipment as well as the definition of their reliability curves by historical surveys about its failure events or preventive replacements, occurred during their entire operation lifetime, in order to establish the optimal lifetime for these equipment for its preventive replacements without operational impacts. As a final result, it’s established a reliability temporal model for the equipment under this study, as well as the ideal lifetime for its preventive overall or replacement based on a certain defined reliability in order to expect its normal operation within that foreseen period under normal operating conditions. However, there are difficulties for the full development of the work, such as sufficient historical background for sampling of failures / successes about those equipment whether the possibility of wrong records events which could be not intrinsic for the equipment (like external fails, errors of operation, operation out of recommended range by the manufacturer, among others). Another difficulty is related to obtaining consensus to define the expected feasible reliability parameter for the equipment due to the "zero failure" culture, in comparison with its involved costs. After implementing the improvements to be identified in the involved process (as well as a new maintenance routines based on the reliability studies performed) it is expected the reduction of the failures in those positioners during its new period of operation. In a final analysis, it’s expected a reduction of the cost of Power Plant’s non-programming shutdown or operation in limited conditions due to failures in these positioners (for example, operation with reduced electrical generation during operation under load limitation due to the presence of a positioner failure until a future moment to get a safety turbine’s shutdown for its replacement).