Development of fuel composition measurement technology using laser diagnostics

The purpose of this research is the development of real-time fuel composition measurement technology using laser diagnostics. In recent years, gas turbine combustors have used a diversity of fuels and the diversification of fuel requires the advanced combustion control technologies. By monitoring fuel gas compositions in real time, optimal fuel compositions can be prepared and applied to the gas turbine operations. The active control using measurement results of gas compositions results in combustion stability and the reduction of environmental pollutants. In this study, the real-time measurement equipment of fuel gas compositions was developed using Raman spectroscopy and tunable diode laser absorption spectroscopy (TDLAS). The colinear optical configuration using Raman spectroscopy was newly employed to enhance the signal intensity and stability of the system. It was demonstrated that it detected the composition of gas turbine fuels within 2 s using Raman spectroscopy and 0.3 s using TDLAS within the relative standard deviations of 1-3%. It also showed the robustness to fine particles in gases, which has proved its applicability to actual gas turbines. The developed system was applied to a 300 MW commercial gas turbine combustor to monitor the fuel gas composition and gas heating value and showed the 240 s faster response time to the conventional gas chromatography method.