Session: 04-24 Kinetics I

Paper Number: 128989

128989 - An Optimized and Reduced Chemical Kinetic Model for CFD Simulations of Hydrogen and Natural Gas Blends Combustion for Industrial Gas Turbines 

Natural gas typically consists of methane, ethane, propane, and trace amounts of higher hydrocarbons. It is one of the common fuels that is used in gas turbines for power generation. Due to its interest in power generation and other applications, there are several chemical kinetic models available in the literature for natural gas. Recently, the power generation sector is moving towards decarbonization and there has been increased interest in replacing conventional fuels with fuels that produce less/zero carbon emissions. One such fuel is hydrogen. However, pure hydrogen has a very wide flammability range and poses risks related to flashback and high thermal NOx production. Hence using 100 % hydrogen as fuel in gas turbines requires significant modifications to existing infrastructure and development of novel combustors. However, blending hydrogen with natural gas helps in having better control over the fuel properties. Before utilizing hydrogen-blended natural gas in a real gas turbine combustor, thorough simulation studies are required to evaluate possible hazards and emissions. However, the literature lacks well-validated chemical kinetic models for the combustion of hydrogen blended natural gas for undilute mixtures at gas turbine relevant conditions (8 - 16 bar). Most of the models available in the literature have been developed for fuels extremely diluted in diluents like argon or nitrogen. Additionally, upon validation with experimental ignition delay times from hydrogen combustion, we found that none of the models available in the literature can predict experimental results accurately at all conditions. Hence, in this work, we develop a detailed chemical kinetic model for hydrogen blended natural gas and validate it with a wide range of experimental data for both dilute and undilute mixtures relevant to gas turbine operating conditions. We outline the strengths and weaknesses of the current mechanism to aid future users of our chemical kinetic mechanism. The detailed chemical kinetic mechanism is then reduced to two smaller versions (60 species and 44 species mechanisms) without significant loss in accuracy using flux analysis and direct relation graph with error propagation (DRGEP). To improve the prediction for pure hydrogen combustion, while retaining all other predictive capabilities, an optimization is carried out for the most sensitive reactions for hydrogen combustion. The resultant mechanism can predict a wide range of experimental results with the least cumulative error. A model CFD study is carried out on FlameSheet® to understand the impact of the new model compared to the models available in literature and the conclusions are outlined.

Presenting Author: Ramees Khaleel Rahman University of Central Florida

Presenting Author Biography: Dr. Khaleel Rahman is a Postdoctoral research associate at the University of central Florida.

Authors:

Ramees Khaleel Rahman University of Central Florida
Raghu Kancherla Power Systems Mfg., LLC
Gregory Vogel Power Systems Mfg., LLC
Subith Vasu University of Central Florida