Experimental Study of Natural Gas and Hydrogen Cofiring Characteristics Using Different Types of Single Nozzles of F-Class Practical Gas Turbine Combustors

Abstract

Recent research on cofiring natural gas and hydrogen, a carbon-free clean fuel, aims to reduce greenhouse gas emissions from aging gas turbine power generation, a key energy issue. This approach can enhance old gas turbines and increase the proportion of combined cycle power plant utilization as coal-fired power plants in Korea gradually shut down. This study seeks optimal operating conditions for mixed fuels without modifying the F-class gas turbine combustor. Experiments were conducted using four different types of fuel nozzles (F-Class DLN combustors) under varying loads and cofiring rates. The test used actual machine operating conditions from 30% to 100% thermal load, with hydrogen cofired with natural gas up to 70% at each load. OH high-speed imaging and an OH-PLIF technique analyzed flame structure and characteristics. Dynamic pressure was measured to check combustion instability, and exhaust gas emissions were evaluated for combustion characteristics. Key findings include critical cofiring rates for each nozzle based on NOx emission levels and combustion dynamics. As the hydrogen cofiring rate increased, flame length decreased, and NOx levels rose rapidly beyond 30%vol. Dynamic pressure oscillations showed no significant variations compared to natural gas combustion. This study successfully derived a characteristic operation map for a single nozzle based on the hydrogen cofiring rate.