Gas Turbine Inlet Salt Monitoring for Filtration and Hot Section Prognostics

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Gas Turbine Emerging Technologies Code 934 has been working, in conjunction with Vibro-Meter Incorporated, to evaluate and further develop the Vibro-Meter Flame Contaminant Detector (FCD). This device has been used on various commercial gas turbine platforms to quantify the level of sodium entrained in fuel. The FCD consists of a spectrometer device, fiber optic cabling, and a lens assembly, which is mounted in an open combustor port. The combustion flame is continuously monitored for sodium wavelength intensity during gas turbine operation. The FCD was initially of interest to NSWCCD for use in fuel filtration system health monitoring. However, based on known Ship Service Gas Turbine Generator (SSGTG) hot section corrosion issues, it was believed that the FCD would also serve as useful tool for quantifying inlet air salt concentration. Testing was performed at the Philadelphia Land Based Engineering Site in 2003. It was determined that the FCD was able to detect salt concentrations as low as 0.003 parts per million. Initial indications are that airborne salt can be differentiated from fuel entrained salt based on continuous vs. intermittent sodium levels. Continuing efforts are centered on optimizing the existing FCD algorithm to properly differentiate between and quantify inlet air and fuel-entrained salt concentration.