The effects of particle grinding on the burnout and surface chemistry of coals in a drop tube furnace

Char particle emissivity of two coal chars in oxy-fuel atmospheres

“…Potential burn out effects, which contain reduction in carbon content with simultaneous enrichment of ash at the particle surface [18], changes of the porosity [19,20] and the carbon structure [21,22] are not measured at high temperature conditions yet, which might be relevant for char particles in later conversion stages. Former investigations have shown, that particle emissivity changes with conversion [15], as the carbon-to-ash ratio and also the particle structure (size and porosity) are known to change with increasing conversion.…”

“…the reduction in carbon content with simultaneous enrichment of ash at the particle surface [18], changes of the porosity [19,20] and the carbon structure [21,22] are also known to be influencing factors on the particle emissivity. Itaya et al investigated the radiation properties of fine char particle clouds.…”

Investigating char agglomeration in blast furnace coal injection

“…In order to simulate the injection of coal into the blast furnace, a drop tube furnace (detailed in [15,33] and shown in Fig. 1) was used.…”

“…This is not likely to be a chemical effect (due to precautions taken in the grinding method), rather an impact of increased numbers of individual particles being injected at a given time. Additionally, the violent fragmentation effect that occurs during injection of larger granulated coals [15] will serve to separate individual particles during injection thus disrupting particle combinations.…”

“…Under certain conditions, coal is prone to physical changes including swelling, fragmentation, and agglomeration [15][16][17][18][19] all of which will go on to impact particle reactivity. Upon the initial heating of a coal particle, caking coals are prone to developing plasticity, often occurring simultaneously with devolatilisation.…”