Sensitivity to change in laminar burning velocity and Markstein length resulting from variable hydrogen fraction in blast furnace gas for changing ambient conditions

摘要

The sensitivity to changes in fuel characteristics has been investigated for combustion of Blast Furnace Gas resulting from small volumetric increases in H_2 concentration. A nonlinear methodology has been employed to quantify unstretched flame speeds and the effect of flame stretch from outwardly propagating spherical flames. Following benchmarking work with CH_4, results were obtained under ambient conditions of 303 K and 0.1 MPa, with small absolute change in hydrogen concentration shown to at least triple the laminar burning velocity for all tested mixtures. Fuel composition and equivalence ratio were shown to independently influence mixture diffusivity and Lewis number, quantified by change in the obtained values of Markstein length. Temperature and pressure were increased to respective values of 393 K and 0.2 MPa to investigate influence of ambient conditions, with a power law correlation presented. Finally the performance of several published chemical reaction mechanisms has been evaluated through comparison of 1-D flame models.