Effects of compositional uncertainties in cracked NH3/biosyngas fuel blends on the combustion characteristics and performance of a combined-cycle gas turbine: a numerical thermokinetic study

Soyler, Israfil, Zhang, Kai, Jiang, Xi and Karimi, Nader (2024) Effects of compositional uncertainties in cracked NH3/biosyngas fuel blends on the combustion characteristics and performance of a combined-cycle gas turbine: a numerical thermokinetic study. International Journal of Hydrogen Energy, 69, 504-517. (doi:10.1016/j.ijhydene.2024.05.013).

Abstract

Blending of partially cracked ammonia with biosyngas is an attractive strategy for improving NH₃ combustion. In practice, products of biomass gasification and those of thermo-catalytic cracking of NH₃ are subject to some compositional uncertainties. Despite their practical importance, so far, the effects of such uncertainties on combustion systems remained largely unexplored. Hence, this paper quantifies the effects of small compositional uncertainties of reactants upon combustion of partially cracked NH₃/syngas/air mixtures. An uncertainty quantification method, based on polynomial chaos expansion and a data-driven model, is utilised to investigate the effects of uncertainty in fuel composition on the laminar flame speed (S_L) and adiabatic flame temperature (T_ad) at different inlet pressures (P_i). The analysis is then extended to the power output of a combined-cycle gas turbine fuelled by the reactants. It is found that 1.5% fuel compositional uncertainty can cause 12–21% of S_L uncertainty depending on the inlet pressure. Furthermore, the effect of compositional uncertainty on Tad increases at higher ratios of H₂ to NH₃. Sensitivity analysis reveals that the uncertainty of CO contribution to S_L uncertainty is higher than that of NH₃, while the trend is reversed for the T_ad uncertainty. In addition, the power output from the combined-cycle gas turbine system varies between 4 and 6% with 1.5% of fuel compositional uncertainty. This become more noticeable at elevated P_i [5–10 atm], particularly when the fuel mixture contains high H₂ which is the main contributor to T_ad variability.

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Contributors

Author: Nader Karimi

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