Slagging occurs in boiler furnaces
where ash deposits are exposed to the
radiant heat of the coal flames, while
fouling occurs in the boiler’s
convective passes. The propensity of a
coal or a blend of coal with other fuels
for producing slagging and fouling
deposits depends on its ash content and,
more importantly, the composition of
that ash, and how the ash behaves under
the conditions within the boiler during
and after the combustion of the
accompanying carbonaceous matter.
The fact that the propensity for slagging
and fouling problems is governed by
the complex interaction between a
boiler’s operating conditions and the
coal ash chemistry makes the prediction
of slagging and fouling very difficult.
Excessive ash deposits on a coalfired
boiler’s heat transfer surfaces will
reduce its efficiency, and in extreme
cases a boiler can be shut down by ashrelated
problems. It has been estimated