Thermocouples have been installed in gas turbine exhaust gas paths for decades for control functions. Since the late 1970s, such thermocouples have also been used for combustion monitoring. The purposes for these thermocouples and the use of the information they provide are sometimes misunderstood. When properly situated and incorporated into a control system, these devices provide data that can ensure a properly operating combustion system, prevent catastrophic hot parts failures, extend component life, and increase availability. Although the use of blade path thermocouples for combustion monitoring has generally been associated with later model gas turbines using cannular combustors, their advantages can also be realized by the modification of older cannular gas turbines as well as turbines with annular or silo combustors. This paper reviews the concept and summarizes the benefits of blade path monitoring and the use of the temperature information obtained. A recommendation is made for the retrofit of older engines and the enhanced instrumentation of some later frames.

This content is only available via PDF.