Holm, PL
1992
Ash Particle Size and Composition Evolution During Combustion of Synthetic Coal and Inorganic Mixtures
Zygarlicke, C.J.; McCollor, D.P.; Benson, S.A. and Holm, P.L.
Twenty-Fourth Symposium (International) on Combustion, The Combustion Institute, Sydney, Australia, July 1992. Funded by US Department of Energy, Energy & Environmental Research Center and ACERC.
Synthetic coal model mixtures were used to determine the chemical and physical transformation mechanisms involved in the evolution of fly ash during combustion. Two calcium, silica, and sulfur synthetic coal systems were prepared: on system containing calcium as 10-µm calcite (Ca[min.]-Si-S), and the other containing calcium as ionically dispersed calcium acetate (Ca[org.]-Si-S). A third system consisted of sodium, silica, and sulfur with the sodium associated as sodium benzoate (Na[org.]-Si-S). Silica, in all three systems, consisted of a furfuyl alsohol/p-toluensulfonic polymer. The synthetic coal mixtures, each sized to 38-106 µm, were combusted in a bench-scale drop-tube furnace at gas temperatures of 900º, 1100º, 1300º, and 1500ºC and residence times of approximately two seconds. Fly ash produced from the Ca(min.)-Si-S mixture revealed significant interaction between the calcite and quartz at higher temperature, as evidenced by increases in particle size and in the levels of amorphous calcium silicate with increasing temperature. Temperatures were high enough to decompose calcite to calcium hydroxide and calcium oxide, which in turn reacted with sulfur o quartz. During the combustion of the Ca(org.)-Si-S mixture, the organically associated calcium reacted primarily with the surface of quartz grains at all temperatures. For both Ca-Si-S systems, calcium reacted with sulfur to form anhydrite at temperatures at or lower than 1300ºC. The Na(org.)-Si-S system revealed extensive melting, mineral particle coalescence, and formation of sodium sulfate at 900ºC; however, at 1500ºC, the fly ash contained only minuscule amounts of sodium or sodium-bearing phases and showed evidence for either char fragmentation or noncoalescence due to the absence of sodium sulfates and silicates.
Holm, PL
1992
Ash Particle Size and Composition Evolution During Combustion of Synthetic Coal and Inorganic Mixtures
Zygarlicke, C.J.; McCollor, D.P.; Benson, S.A. and Holm, P.L.
Twenty-Fourth Symposium (International) on Combustion, The Combustion Institute, Sydney, Australia, July 1992. Funded by US Department of Energy, Energy & Environmental Research Center and ACERC.
Synthetic coal model mixtures were used to determine the chemical and physical transformation mechanisms involved in the evolution of fly ash during combustion. Two calcium, silica, and sulfur synthetic coal systems were prepared: on system containing calcium as 10-µm calcite (Ca[min.]-Si-S), and the other containing calcium as ionically dispersed calcium acetate (Ca[org.]-Si-S). A third system consisted of sodium, silica, and sulfur with the sodium associated as sodium benzoate (Na[org.]-Si-S). Silica, in all three systems, consisted of a furfuyl alsohol/p-toluensulfonic polymer. The synthetic coal mixtures, each sized to 38-106 µm, were combusted in a bench-scale drop-tube furnace at gas temperatures of 900º, 1100º, 1300º, and 1500ºC and residence times of approximately two seconds. Fly ash produced from the Ca(min.)-Si-S mixture revealed significant interaction between the calcite and quartz at higher temperature, as evidenced by increases in particle size and in the levels of amorphous calcium silicate with increasing temperature. Temperatures were high enough to decompose calcite to calcium hydroxide and calcium oxide, which in turn reacted with sulfur o quartz. During the combustion of the Ca(org.)-Si-S mixture, the organically associated calcium reacted primarily with the surface of quartz grains at all temperatures. For both Ca-Si-S systems, calcium reacted with sulfur to form anhydrite at temperatures at or lower than 1300ºC. The Na(org.)-Si-S system revealed extensive melting, mineral particle coalescence, and formation of sodium sulfate at 900ºC; however, at 1500ºC, the fly ash contained only minuscule amounts of sodium or sodium-bearing phases and showed evidence for either char fragmentation or noncoalescence due to the absence of sodium sulfates and silicates.