Comparison of Reburning with
Post-Combustion Control
Technologies
Reburning involves combustion
modification. Competing technologies
for coal-fired boiler NOx control are
post-combustion processes such as SCR
and SNCR. SNCR operates in a fashion
that has some of the characteristics of
reburning. In SNCR, instead of generating
the NOx-reducing species from
the decomposition of fuel, as is done in
reburning, the reducing agent (typically
ammonia or urea) is injected into the furnace
above the combustion zone, where
it reduces the NOx to nitrogen and water.
NOx reduction efficiency for SNCR may
be in the same range as that for reburning,
but efficiency varies with boiler capacity,
furnace configuration, etc.
SCR, in which the NOx reduction is
carried out over a catalyst, has the capability
of greater NOx reduction but is more
expensive than SNCR. SCR, like reburning,
is applicable to virtually any type
of power generation or industrial boiler.