Sorbent reactivation has received attention for
over 25 years [1,2] and, even earlier, hydration of
calcined limestone had been shown to improve its
performance as a sorbent for sulphur dioxide at
fluidized bed combustion (FBC) temperatures [3].
However, even now reactivation by hydration is still
not a routine process for FBC boilers firing highsulphur
fuels. The essential question is why, after
such considerable efforts, has so little progress been
made? To answer this and some other important
questions, this paper looks at the most important
issues that are responsible for the complexity of
what might at first sight appear as a simple matter.
In particular, in many studies ‘‘model’’ bed ash has
been used, derived from the sulphation of pure
limestone-based sorbents under laboratory