
94 Conversion of Large Scale Wastes into Value-added Products
At the higher pressures of PFBC, the high partial pressure of CO
2
prevents
decomposition of CaCO
3
and sulfur capture occurs by direct sulfation:
CaCO
3
(s) + SO
2
(g) + ½O
2
(g) → CaSO
4
(s) + CO
2
(g)
As with y ash and bottom ash produced by pulverized coal combustion, the
composition of ash generated by uidized bed combustion can be quite variable.
While fuel quality and composition determine a portion of the ash chemistry, sorbent
composition is a major factor because it is such a large proportion of the by-product
produced. Other factors such as operating conditions also contribute to ash ...