Assessment of Gas Turbine Vibration Monitoring

This paper presents a basis for selecting and justifying vibration monitoring equipment for power-generating gas turbines. Users of industrial gas turbines from utility and petrochemical companies are surveyed; a utility forced outage data base is analyzed; typical vibration limits are presented; and the current capabilities of commercial monitoring systems and vibration transducers are summarized. The industry survey by site visits and questionnaire develops common trends; it itemizes malfunctions that can be successfully identified with appropriate vibration monitoring; it summarizes current practices, benefits, limitations, and operating experience with various transducer types, as applied to harsh gas turbine environments. Vibration limits, trending, and sources of vibration are addressed. Operational factors are considered in planning and cost justifying vibration monitoring systems for a basic trip protection, periodic measurements, and on-line computerized continuous protection. Seventeen case histories and examples illustrate and support these findings. Analysis of the utility-generated data base complements the industry survey; it isolates the contribution of different vibration-related outages for base loaded and peaking units; graphic results break down these outages into duration, man-hours to repair, and frequency of occurrence.