(273d) Effect of Composition Variation of Syngas Mixtures on NOx Formation at High Pressure

Increasing interest in syngas combustion in gas turbines has led to highlighting the environmental feasibility, in particular the control of nitrogen oxide (NO_x) emissions. Trace amounts of NO_x species may be present during combustion and lean premixed (LPM) combustion method is one of the effective NO_x control technologies for gas turbines. Despite the proven feasibility of syngas, these fuels face variation in their composition due to different feedstock and production methods. Syngas can contain small amounts of hydrocarbons, such as methane, ethane and ethylene, and the presence of hydrocarbon species in the fuel can affect the NO_x emissions in the post-flame region. A detailed investigation of high-pressure syngas combustion is required to provide both practical information regarding NO_x emissions from gas turbine systems and fundamental understanding of reaction pathways to verify and develop chemical kinetic models.

In this study, a high-pressure burner facility capable of operating at pressures up to 15 bar, was designed and fabricated to simulate syngas combustion in a gas turbine. Syngas consisting mainly of H₂ and CO was blended with components such as nitric oxide (NO), nitrogen dioxide (NO₂) and trace amount of hydrocarbons prior to combustion at high pressure. Hot combustion products were supplied to the high pressure vessel by a flat flame burner operating with lean, premixed syngas-air mixtures with various H₂/CO ratios ranging between 0.25-1.0 and equivalence ratios between 0.5-1.0. Detailed NO_x speciation measurements in the post-flame region were conducted for different fuel compositions at various pressures up to 10 bar using Fourier transform infrared (FTIR) spectrometer. The experimental data generated from this project can be used to validate/develop kinetic models to predict NO_x emissions.