Kinetic Modeling of the Premixed Combustion of Blast Furnace Gas and Effects of Variable Compositions

ABSTRACT: Blast furnace gas (BFG) is an important residual fuel gas formed in the blast furnaces. Its utilization for heating and power generation improves the overall energy efficiency of steel industry. In this work, the premixed combustion of BFG and air combustion was investigated with particular emphasis on the variations in composition of BFG. Fundamental properties of the premixed laminar flame and chemical reactions were estimated with the help of the USC Mech. II comprehensive kinetic model developed for the combustion of CO/H2/C1-C4 mixtures. Predictions of the kinetic model were validated on a large set of experimental data for BFG-air flames and one syngas-air dataset covering phi = 0.7-1.5, T = 298-393 K, P = 0.1 MPa, and multiple compositions, without requiring ad hoc changes in the default rate parameters. Flame structure and flame properties were analyzed with the help of reaction path analysis, rate of production analysis, and sensitivity analysis. Results of these analyses showed that H2 chemistry influences the propagation of stable BFG-air flames. A detailed uncertainty analysis was carried out to reveal the significant effects of compositional variations on the flame temperature and burning velocity of a well-mixed BFG-air mixture. The analysis showed variations in the range 4.2-22.5 cm/s and 1195-1731 K for laminar burning velocity and flame temperature, respectively. Correlations were developed using the uncertainty analysis showing that H2 affects the burning velocity and CO affects the flame temperature. The uncertainty analysis could be a useful tool to determine the operating conditions for a well-mixed fuel-flexible combustor.