PITTSBURGH, PA - A new technology recently evaluated
on a type of coal-fired boiler notorious for generating the air pollutant
known as NOx was found to reduce NOx formation by 90 percent at about
half the cost of current technologies.
Known as the Advanced Layered Technology Approach, or ALTA, the technology
was field-tested this summer at AmerenUE’s Sioux Unit 1 Station
near St. Louis, Mo., using a blend of Powder River Basin and Illinois
coals in a 500-megawatt cyclone boiler. The results have led the utility
to reconsider its plans to install another NOx-control technology, called
selective catalytic reduction, in favor of ALTA. Ameren is now evaluating
full-scale implementation of ALTA technology in both 500-megawatt units
at the Sioux Power Plant, with potential installation anticipated in 2006.
|Ameren’s Sioux Unit 1 has demonstrated the
first in-furnace control technology that achieves NOx emissions below
0.15 pounds per million Btu on a coal-fired cyclone boiler—a
90 percent reduction over the unit’s baseline NOx emissions—at
half the cost of current technologies. Ameren is now reconsidering
its plans to install standard NOx-control technology in favor of ALTA.
The field test is one of
five advanced NOx-control projects recently awarded contracts through
the Department of Energy’s Innovations for Existing Plants Program,
managed by the National Energy Technology Laboratory. The overall goal
of the program is to enhance the efficiency and environmental performance
of existing coal-fired power systems as part of DOE’s commitment
to clean coal technology.
ALTA uses a strategic combination of overfire air, rich reagent injection,
and selective non-catalytic reduction processes in the boiler to reduce
NOx formation and ammonia slip. The ALTA technology also shares equipment
such as tanks, pumps, and injection components between the selective non-catalytic
reduction and rich reagent injection systems to reduce the capital costs
for installation and operation.
In short-term field testing, the Sioux Unit 1 demonstrated for the first
time that an in-furnace control technology can achieve NOx emissions below
0.15 pounds per million Btu on a coal-fired cyclone boiler. With the ALTA
technology, NOx emissions were 0.12 pounds per million Btu firing the
typical blend of 80 percent Powder River Basin coal and 20 percent Illinois
coal, and they were as low as 0.165 pounds per million Btu firing 100
percent Illinois coal.
|Modeling had shown that the injection of an ammonia-rich
chemical compound would reduce NOx emissions in a cyclone boiler from
1.2 to 0.35 pounds per million Btu. The same results have now been
obtained in the field-testing of a standard-size unit. Combining this
technology with a selective non-catalytic reduction process further
pushed emissions down, to 0.15 pounds per million Btu.
The 0.12 pounds per million Btu NOx level represents a 90 percent reduction
from the Sioux Unit 1 pre-overfire air baseline emissions. The ALTA technology
results in emission levels that will help to meet the EPA’s recently
announced Clean Air Interstate Rule for NOx limits.
The field test was a collaborative effort led by Reaction Engineering
International (REI) working with Ameren, EPRI, and FuelTech, Inc. Rich
reagent injection was co-developed by EPRI and REI with funding from DOE-NETL.
It is licensed to REI, who in turn has sublicensed it to FuelTech Inc.
and Combustion Components Associates.