Optical Analysis of Blast Furnace Gas Combustion in a Laboratory Premixed Burner

The use of blast furnace gas (BFG) as a fuel provides an alternative for waste stream valorization in the steel industry, enhancing the sustainability and decarbonization of its processes. Nevertheless, the implementation of this solution on an industrial scale requires a continuous control of the combustion due to the low calorific value of BFG. This work analyzes the combustion behavior and monitoring of BFG/CH₄ blends in a laboratory premixed fuel burner. We evaluate several stable combustion conditions by burning different BFG/CH₄ mixtures at a constant power rate over a wide range of air/fuel equivalence ratios. In addition, relevant image features and chemiluminescence emission spectra have been extracted from flames, using advanced optical devices. BFG combustion causes an increase in CO₂ and CO emissions, since those fuels are the main fuel components of the mixture. On the other hand, NO emissions decreased because of the low temperature of combustion of the BFG and its mixtures. Chemiluminescence shows that, in the case of CH₄ combustion, peaks associated with hydrocarbons are present, while during the substitution of CH₄ by BFG those peaks are attenuated. Image flame features extracted from both ultraviolet and visible bandwidths show a correlation with the fuel blend and air/fuel equivalence ratio. In the end, methodologies developed in this work have been proven to be valuable alternatives with a high potential for the monitoring and control of BFG cofiring for the steel industry.