Effects of initial condition and fuel composition on laminar burning velocities of blast furnace gas with low heat value

Abstract

Laminar burning velocities of blast furnace gas with low heat value were investigated using constant volume combustion chamber and CHEMKIN package. Experiments and numerical simulations using Li, Davis, Gri-Mech 3.0, San Diego Mech, USC Mech II, NUI Galway Mech models were conducted at initial pressures of 0.1–0.2 MPa, initial temperatures of 303–453 K, and equivalence ratios of 0.8–1.6. Fuel composition was changed considering the volume fraction variation in blast furnace gas with calorific values of 3.27–4.03 MJ/m3. The effects of initial pressure and temperature on laminar burning velocities were correlated with high-order polynomials dependent on the equivalence ratio. The thermal and transport effects were examined and sensitivity analyses were further conducted to study the chemical kinetic effect. The results show that the laminar burning velocities increase with the decrease of initial pressure and the increase of initial temperature, and the Gri-Mech 3.0 mechanism gives very good predications among the six kinetic mechanisms. In addition, the laminar burning velocities increase with the increase of H2/CO ratio and the decrease of CO2/N2 ratio under the same low heat value. The chemical kinetic effect plays a major part during the laminar flame propagation under all the operation conditions considered. Due to the high CO content and low H2 content in blast furnace gas, R99 and R45 are the main chain branching and chain termination reactions, respectively. The effects of initial condition and fuel composition on laminar burning velocities are closely related to the concentrations of H, O and OH radicals.