Numerical study of natural gas and low-calorific syngas co-firing in a pilot scale burner

Abstract In this work, the possibility of the natural gas and syngas co-firing was numerically and experimentally investigated. The computational fluid dynamics (CFD) modelling of an exemplary, commercial, natural gas burner was conducted to analyse the natural gas and syngas co-firing in an unmodified burner. It was found that only at a lower syngas thermal share (10%) it was possible to co-fire the natural gas and syngas, but when a higher thermal share of syngas (40%) was considered, it was difficult to co-fire natural gas and syngas due to the increase of the flow resistance and high velocities of the gas mixture. Burner modifications were proposed to address these issues but required significant construction changes. Therefore, a new burner geometry was proposed in order to provide stable natural gas and syngas co-firing. The new design was numerically investigated in different configurations and operating conditions and experimentally tested. The pilot test experiments confirmed that the new burner designed for natural gas and syngas co-firing exhibited a stable flame in a wide range of operational conditions. On this basis, three scaled-up burners (400 kW) were manufactured and installed in a preheating furnace in the steel sector.