This work addresses combustion efficiency and NOx emission measurements on a boiler system fired by a 0.5 MWth iron powder burner. This represents a scale-up towards an industrial prototype compared to previously reported systems. Roughly 10 tonnes of two commercially available powders were combusted with mean diameters of 57 and 85 μ m. Continuous operation was obtained up to 9 h, and heat was successfully extracted via steam. The combustion efficiency was found to be 70%–80%. NOx emissions (including the propane pilot flame) was between 5–10 mg/MJ. The NOx emissions are well below the European requirement for ultra low NOx gas burners (EN 676 Class4, 16.7 mg/MJ). Both combustion efficiency and NOx emissions are comparable to values obtained in lab-scale burners. This work is the first report of a semi-industrial scale boiler running on iron combustion. It identifies two challenges: increasing the combustion efficiency and; design of a burner that can operate without a (propane) pilot flame. This paves the way to large scale implementation of iron powder as an energy carrier. • First ever results of an semi-industrialscale boiler running on iron combustion. • The produced oxides and heat were succesfully extracted from the system. • Combustion efficiency averaged around 70%–80% • NOx emissions measured ranged between 5–10 mg/MJ. • Combustion efficiency & NOx emissions are similar to those of lab-scale burners.
Rooij et al. (Fri,) studied this question.