Investigation of flame evolution and stability characteristics of H2-enriched natural gas fuel in an industrial gas turbine combustor

Abstract

Enhancing the H2 blending ratio in industrial gas turbines is essential to reduce fossil energy consumption and achieve carbon neutrality. However, several uncertainties still exist in their safe operation with H2 addition. In this work, a numerical investigation is conducted to evaluate the behavior and combustion stability of an H2-enriched natural gas fuel premixed swirl flame in an industrial gas turbine. The results indicate that the flame exhibits three types of behaviors upon increasing the H2 blending ratio, i.e., stable combustion, central flashback, and boundary layer flashback. The flame structure is highly sensitive to the inlet air temperature. The combustion reaction zone moves to the swirler as the inlet air temperature decreases, which in turn aggravates the central flashback. Injecting recirculated flue gas into the inlet air is proposed to restrain the central flashback. It is found that the flashback and blow-out limits exhibit quadratic polynomial and linear relationships with the recirculated flue gas ratio, respectively. The laminar flame speed of H2-enriched natural gas premixed flames with recirculated flue gas dilution at the flashback limit is 35.8 ± 0.5 cm/s. It is recommended to design or control H2-blended gas turbine burners with a laminar flame speed to ensure operational safety.