A quantitative analysis of the ignition characteristics of fine iron particles

Particle Equilibrium Composition model for iron dust combustion

“…The use of this reaction rate makes the ignition model valid for limited conditions. Including an ignition model such as Mi et al [25] can improve this. However, for this work it is expected that including the ignition model of Mi et al will only have an impact on the height of 𝑠 L and does not influence the shape of the 𝑠 L curve.…”

“…Therefore, the conversion from iron to iron oxide is governed by surface reactions, where the dispersed phase consumes oxygen from the gas phase, forming iron oxides. Ignition is governed by surface kinetics, quickly followed by melting and thermal runaway [25]. The conversion of Fe to FeO is generally accepted to occur in the diffusionlimited regime, see [2,8,12,25].…”

“…Ignition is governed by surface kinetics, quickly followed by melting and thermal runaway [25]. The conversion of Fe to FeO is generally accepted to occur in the diffusionlimited regime, see [2,8,12,25]. As a first step, it is assumed that all transport and kinetic processes inside the particle are much faster than external processes, i.e.…”

Combustion, Chemistry, and Carbon Neutrality

“…555 Insight is needed into the oxygen interaction with the particle, phase changes, solid-and liquid-state reactions during the oxidation, heat exchange between particles and surrounding gas, and further aspects, to conceive a physico-chemically sound, reliable model of the process that could serve as a basis for upscaling. 555 Experimental investigations whose results could support mechanism development have only just begun to appear. 551−558 Diagnostic monitoring techniques (Section 2.1) for the analysis of iron powder flames and of the oxidation of single metal particles must consider the heterogeneous, three-dimensional nature of the process with luminous, dense multiphase environments and the need for microscopic information on the size and morphology of individual particles.…”

“…Compared to ignition and combustion of solid fuels like coal or biomass where evaporation of volatile matter upon heating plays a role, the process is different for metal particles. Mi et al describe the oxidation of an iron particle as a three-step process, starting from ignition and preheating that leads to thermal runaway, rapid oxidation of a molten droplet until complete consumption of the iron particle, followed by slower oxidation of lower oxidized products (FeO, Fe 3 O 4 ) to Fe 2 O 3 . They raise important questions that must be answered for designing a real-world system, regarding ignition, nonvolatile combustion, and kinetics of the energy release during the rapid and slow oxidation steps .…”