Effect of Hydrogen Combustion on the Combustion Dynamics of a Natural Gas Combustor

Abstract

In a carbon-constrained world, Integrated Gasification Combined Cycle (IGCC) systems achieve excellent environmental performance and offer a more economical pre-combustion CO2 removal compared to other coal-based systems. The residual gas after carbon removal is comprised primarily of hydrogen and nitrogen mixtures. Achieving stable combustion of hydrogen-rich fuel mixtures while producing ultra-low NOx emissions (much lower than current diffusion combustion technology) is challenging. The goal of this study was to characterize the stability of lean premixed combustion systems operating with hydrogen and establish boundaries for stable operation. Modeling and experimental efforts were directed towards demonstration of the feasibility of such systems while meeting the emissions requirements. The higher flame speed and heat-release rate achievable with hydrogen-containing fuels can change the dynamics and stability characteristics of the combustors compared to natural gas. A combustion rig was modeled using an in-house combustion dynamics analysis code. In the model, flame heat-release fluctuations were captured by considering the effect of upstream fuel-air ratio fluctuations and flow speed fluctuations. CFD simulations were used to obtain combustion parameters. The results showed the effect of using hydrogen instead of methane and the simulations correctly predicted the combustor modes and their instability for hydrogen as well as methane combustion.