M. Garcia-calzada et al., Stability and oxidative stabilisation of sulphided calcareous sorbents from entrained flow gasifiers, CHEM ENG SC, 55(18), 2000, pp. 3697-3714
The stability of different sulphided materials (pure CaS particles, sulphid
ed calcium hydroxide, sulphided limestone, sulphided dolomite and sulphided
calcium magnesium acetate) when exposed to a moistened stream of air at am
bient conditions has been studied. For all the analysed sorbents, the relea
se of H2S during exposure to a moistened stream of air is a function of the
calcium sulphide content of the sorbent. The ratio between the amount of r
eleased sulphur and the amount of sulphur stabilised as sulphate or element
al sulphur is also a function of the initial calcium sulphide content of th
e sorbent. Additionally, the performance of air oxidation at different temp
eratures (800-980 degrees C) for stabilisation of the sulphided sorbents ha
s been analysed. The final apparent conversion achieved during air oxidatio
n of the sulphided sorbents, including particles of sulphided calcium aceta
te, in the temperature range 800-980 degrees C shows an inverse dependence
with the (calcium sulphide content)/(specific surface area) ratio of the so
rbents. The total amount of SO2 released during air oxidation at high tempe
rature is a function of the initial calcium sulphide content of the samples
. Conversion degrees up to 100% have been obtained. For all sorbents, the c
onditions for complete stabilisation and negligible SO2 release during oxid
ation were established. The differences found in final oxidation conversion
s and stability of the oxidised sorbents for increasing oxidation temperatu
res can be explained in terms of the oxidation mechanisms for low (< 890 de
grees C) and high temperatures. (C) 2000 Elsevier Science Ltd. All rights r
eserved.