Market Potential
Reburning is applicable to all types
of coal-fired boilers, including the major
types of firing systems used in electric
power generation and industrial steam
production, specifically wall-fired, T-fired,
cyclone, and stoker units. A significant
feature of reburning is that it can be used
on cyclone boilers, whose design features
do not lend themselves to being retrofitted
with LNBs.
Reburning can be used as an alternative
to LNBs or in combination with LNBs to
meet Title IV NOx emissions regulations.
A large potential market for reburning is
the boilers subject to more stringent controls
under Title I of the CAAA. Illustrative
of this market are the boilers covered
under EPA’s September 1998 Rule for
Reducing Regional Transport of GroundLevel
Ozone. As discussed previously,
this rule requires 22 states and DC to
submit revised State Implementation
Plans to ensure that emissions are sufficiently
reduced to mitigate transport of
ozone and NOx across state boundaries
in the Eastern half of the United States.
All boilers in this region, as well as
those located in other ozone nonattainment
areas across the U.S., are potential
candidates for retrofit reburning applications.
While reburning alone cannot meet
the stringent NOx emissions requirements
associated with Title I, reburning can be
Canada geese feeding in shadow
of power plant stack.
used along with LNBs to reduce the
load on post-combustion technologies
such as SCR.
Economics
Whether natural gas or coal is used as
the reburn fuel is a decision based largely
on economics. Factors that affect the
comparison are: (a) the cost differential
between gas and coal; (b) the capital and
operating costs of pulverizers and other
coal-handling equipment required for coal
reburning; (c) the availability of natural
gas at the site; (d) the relative impacts
of coal and gas reburning on boiler efficiency;
and (e) the possibility of generating
credits from decreased emissions of
SO2 when burning natural gas.
Although a comparison between these
technologies is highly site specific, in
general the capital cost of coal reburning
is higher than that of gas reburning, primarily
because of the cost of the pulverizers
and ancillary equipment required for
coal reburning, particularly with cyclonefired
boilers, which utilize coarse coal.
However, for some boilers firing pulverized
coal, it may be possible to adjust
the existing pulverizers to achieve a sufficiently
fine particle size for the reburn
coal. If natural gas is not available at the
site, the cost of installing a supply line
from the nearest pipeline to the power
plant may make the capital cost of gas reburning
higher than that of coal reburning.
As opposed to capital costs, which
tend to be higher for coal reburning,
operating costs tend to be higher with
gas reburning because of the gas/coal
fuel price differential. At present, coal
is significantly cheaper than gas per unit
of heat content, and this price differential
is expected to increase over the next
15 years