Laminar Flame Speed Measurements of H2/CO/CO2 Mixtures Up to 15 atm and 600 K Preheat Temperature

Abstract

Laminar flame speeds of lean H2/CO/CO2 (syngas) fuel mixtures have been measured for a range of H2 levels (20–90% of the fuel) at pressures and reactant preheat temperatures relevant to gas turbine combustors (up to 15 atm and 600 K). A conical flame stabilized on a contoured nozzle is used for the flame speed measurement, which is based on the reaction zone area calculated from chemiluminescence imaging of the flame. A O2:He mixture (1:9 by volume) is used as the oxidizer, rather than standard air, in order to suppress the hydrodynamic and thermo-diffusive instabilities that become prominent at elevated pressure conditions for lean H2/CO fuel mixtures. All the measurements are compared with numerical predictions based on two leading kinetic mechanisms: the H2/CO mechanism of Davis et al. and the C1 mechanism of Li et al. The results generally agree with the findings of an earlier study at atmospheric pressure: 1) for low H2 content (<40%) fuels, the model predictions are in good agreement with measurements at both 300 K and 600 K preheat temperature; but 2) the models tend to over predict the temperature dependence of the flame speed for medium (∼40–60%) and high (> 60%) H2 content fuels, especially at very lean conditions. The elevated pressure (∼15 atm) results, however, reveal that the effect is less pronounced than at atmospheric pressure. The exaggerated temperature dependence of the current models may be due to errors in the temperature dependence used for so-called “low temperature” reactions that become more important as the preheat temperature is increased. The radiation effects associated with CO2 addition to the fuel (up to 40%) is found to be less important for medium and high H2 content syngas fuels at elevated pressure and preheat temperature.

Experimental Flame Front Characterisation in a Lean Premix Burner Operating with Syngas Simplified Model

“…The differences in the adopted gasification technology or in the coal quality may lead to large variations in the syngas composition [3]. Such a variation may affect several parameters of the syngas combustion such as the flame speed [4][5], the ignition delay [6][7] and the extinction limit [8].…”

Experimental Flame Front Characterisation in a Lean Premix Burner Operating at Syngas

“…The differences in the adopted gasification technology or in the coal quality may lead to large variations in the syngas composition [2]. Such a variation may affects several parameters of the syngas combustion such as the flame speed [3][4], the ignition delay [5][6] and the extinction limit [7]. Consequently, the combustor design and operation may result largely complicated, especially in the case of gas turbine employ such as in the Integrated Gasification Combined Cycle (IGCC) power plants.…”