A hydrated FBC waste as well as synthetic preparations of calcium hydroxide and ettringite were investigated in a laboratory-scale fluidized bed reactor operating at 850°C under simulated desulphurization conditions. X-ray diffraction analysis, simultaneous differential thermal/thermogravimetric analyses and mercury intrusion porosimetry were the main experimental techniques employed for the materials characterization. The hydration/reactivation of FBC residue was carried out at 70°C for 48 hours with a water/solid ratio equal to 100, giving a hydration product mainly containing ettringite. The hydrated FBC waste showed a good desulphurizing ability due to calcium oxide generated during thermal decomposition of ettringite. When compared to synthetic ettringite, the hydrated FBC waste shows a lower desulphurization efficiency, a greater degree of calcium conversion and a higher attrition propensity. From a comparative evaluation between ettringite and calcium hydroxide it can be drawn that sulphation mainly involves different pore sizes ranges of the two sorbents.
The desulphurizing ability of ettringite formed during the hydration/reactivation of FBC coal fly ash
TELESCA, ANTONIO;VALENTI, Gian Lorenzo
2006-01-01
Abstract
A hydrated FBC waste as well as synthetic preparations of calcium hydroxide and ettringite were investigated in a laboratory-scale fluidized bed reactor operating at 850°C under simulated desulphurization conditions. X-ray diffraction analysis, simultaneous differential thermal/thermogravimetric analyses and mercury intrusion porosimetry were the main experimental techniques employed for the materials characterization. The hydration/reactivation of FBC residue was carried out at 70°C for 48 hours with a water/solid ratio equal to 100, giving a hydration product mainly containing ettringite. The hydrated FBC waste showed a good desulphurizing ability due to calcium oxide generated during thermal decomposition of ettringite. When compared to synthetic ettringite, the hydrated FBC waste shows a lower desulphurization efficiency, a greater degree of calcium conversion and a higher attrition propensity. From a comparative evaluation between ettringite and calcium hydroxide it can be drawn that sulphation mainly involves different pore sizes ranges of the two sorbents.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
