High efficiency low NOX BFG based combustion systems in steel reheating furnaces (HELNOx-BFG) : final report

Within this funded project it has been developed a combustion system for an efficient utilization of blast furnace gas (BFG) in steel reheating furnaces, by means of fuel preheating, so as to maintain the same production level of a high heating value fuel, reducing natural gas dependence, carbon footprint and nitrogen oxides emissions. Firstly, a deep analysis of the impact and potential of the blast furnace gas has been reviewed and limits and constrains of the available commercial technologies have been evaluated based on industrial reheat furnaces data. Secondly, three different breakthrough solutions have been designed, manufactured and tested at both pilot and long-term industrial scale, namely: (a) double regenerative BFG-air-burners, (b) preheated BFG oxy-burner and (c) oxy-BFG-regenerative flat-flame burner. A techno-economical study, retrofitting and operational guidelines have been issued. On the other hand, CFC (Computational Fluid Dynamics) modelling has been developed for BFG firing and used in the burners' design. Several combustion and radiative models have been compared and validated, based on the three technologies experimentally tested. Furthermore, a system analysis for an integrated site was performed, describing the impact of the BFG firing in the European steel industry based on the different boundary conditions. Technologies' safety, performance, reliability and robustness have been assessed, proving that 100 % BFG can be fired in reheating furnaces, achieving typical furnace temperatures and keeping NOX emissions level below the European regulation threshold. Results have been disseminated via scientific publications and conferences.