Opportunities for advanced sensors for condition monitoring of gas turbines

The power generation business is a very competitive market for both the original equipment manufacturers as well as the power utilities. A variety of economic and technical forces have produced large industrial gas turbines with ever increasing levels of efficiency, and operators are now being offered combined-cycle gas turbine plant with efficiencies of 57-60%. Simultaneously the operating companies are under continued pressure to minimise operating and maintenance costs. Since fuel costs represent the main part of the running costs, high efficiency units are attractive, providing they can meet the projected reliability and availability targets. To minimise operator risks it is prudent to seriously consider the level of monitoring a unit requires, and whether this should go beyond that normally offered. It is within this context that the role of sensors and the associated opportunities lie. They provide a fuller picture of the operating conditions within the unit, allowing a move towards a condition monitoring based decision making process for both operational and maintenance issues. This paper provides a review of advanced sensoring techniques for monitoring the condition of gas turbines with particular emphasis on those parameters likely to be affected by the design changes found in the newer units. These include: vibration monitoring; performance monitoring; lubrication system monitoring; pyrometry; and continuous emissions monitoring. Techniques under development are also discussed