Andrzej Rusin
Selection of maintenance range for power machines and equipment in consideration of risk
The operational safety of power units depends upon many factors, including the methods of their operation, their working conditions, age, regularity and range of maintenance. The scope of the paper is the analysis of maintenance options for power machines and equipment. The assumed criterion for the selection of the range of repair works is the level of technical risk posed by a given facility below the accepted allowable level. Detailed discussion is focused on the water and steam system of the boiler. The influence of the maintenance on the probability of failure of certain components is described on the grounds of Kijima's model. For the assumed maintenance periods minimal sets of equipment were determined, the repair of which should secure the operation of the water-steam system for a successive interval with the risk level lower than the allowable one.
Systems of supporting the supervision of the operational safety of steam turbines
The possibilities of supervising the operation of thermal turbines enabling the tracking and prevention of events that may lead to serious failures are discussed. The algorithms of the monitoring the thermal stress levels of particular components are presented, together with brittle cracking hazards on the grounds of failure diagrams. The algorithms are based on typical quantities measured and recorded by the measurement systems of power units as well as on the material characteristics obtained from non-destructive tests.
Optymalizacja okresów międzyremontowych maszyn energetycznych z uwzględnieniem ryzyka
Celem obsług prewencyjnych jak i korekcyjnych jest zachowanie lub przywrócenie akceptowalnego poziomu efektywności i bezpieczeństwa eksploatacji danego obiektu. Optymalizacja działań remontowych pozwala na uzyskanie tych efektów przy możliwie niskich kosztach. W artykule przedstawiono model matematyczny optymalizacji okresów międzyremontowych z uwzględnieniem ryzyka. Szczegółowe obliczenia przeprowadzono dla turbin pracujących w blokach energetycznych dużej mocy.
Optimization of power machines maintenance intervals taking the risk into consideration
The goal of preventive as well as corrective maintenances is to keep or to restore acceptable level of efficiency and safety of operation of given object. Optimization of maintenance processes allows obtaining these effects at possibly lowest costs. Mathematic model of optimization of maintenance intervals having regard to the risk are presented in the paper. Precise calculations were made for steam turbines that operate in power units.
Steam turbine maintenance planning based on forecasting of life consumption processes and risk analysis
Flexible operation of coal-fired power plants contributes to the intensification of the life consumption processes, which is a serious problem especially in the case of units with a long in-service time. In steam turbine rotors, the crack propagation rate and material wear caused by low-cycle fatigue increase. The aim of the research is an attempt to forecast the development of these processes and to estimate the probability of critical elements damage, such as the high-pressure and intermediate-pressure rotors. In the stress state analyses, the finite element method (FEM) is used, the Monte Carlo method and the second order reliability method (SORM) is apply to calculate the probability of failure. It is proposed to use risk analysis to plan preventive maintenance of the turbine. The optimal intervals for carrying out diagnostic tests and prophylactic repairs is determined for various operating scenarios and various failure scenarios. This enables a reduction of the costs while ensuring the safety of the turbine's operation.