Uniform Crystal Temperature Sensor Application on PSM FlameSheet™ Combustor for High Hydrogen Operation

In the pursuit of increasing hydrogen (H2) fuel concentration in large gas turbine combustors used for power generation, full condition rig testing is necessary to prove operational capability and ensure component life. Hydrogen combustion characteristics can vary substantially from traditional natural gas (NG) combustion leading to challenges in maintaining emissions compliance, flame stability and turndown on wide ranges of H2/NG concentration. Typically, multiple modes of operation are required to achieve desirable operational characteristics over the range of H2/NG fuel concentrations which leads to new challenges meeting design life requirements. Accurate metal temperature measurements are critical to combustion hardware life analysis. In recent full condition combustion rig testing of a single combustor on high concentrations of H2, UCTS (Uniform Crystal Temperature Sensor), commonly known as “thermal crystals” were installed to measure peak metal temperatures in a dedicated thermal cycle run. Due to limited access of the area of concern, conventional thermocouples were not installed, and thermal crystals were found to be the best available means of metal temperature measurement. The dome extension to which UCTS were applied is a one component of the PSM FlameSheet™ combustor. It is subject to very high temperature, particularly on high H2 concentration, potentially leading to premature component failure if maximum material temperature limits are exceeded. Small excursions from these material capability temperature limits can yield drastically shortened life resulting in performance degradation from damaged hardware, or worse, shutdown of the unit for repair. Therefore, accuracy of the metal temperature measurements is critical. Results of a successful UCTS test are presented in the paper.