PITTSBURGH, PA -
The Department of Energy has announced four awards totaling $1.4 million
for advanced research to aid the removal of mercury from existing fossil-fueled
power plants. The four new projects support the President’s call
for dramatic cuts in mercury emissions by providing an understanding of
the mechanisms of mercury chemistry, and leading to novel approaches to
measure and remove mercury from flue gas.
Coal contains only trace amounts of mercury, but when coal is consumed
to produce power, gaseous species of mercury are formed and emitted into
the atmosphere. These emissions are the largest human-created source of
mercury emissions in the United States, and may contribute to a variety
of health and environmental problems.
The complex nature of gas mixtures and process conditions in coal-fired
power systems makes it difficult to develop predictable, effective, low-cost
mercury control technologies. To remove the barriers to mercury control,
awards were made in three areas: mercury measurement, removal in post-gasification
cleanup processes, and chemistry and transport in post-combustion pollution-control
processes.
The new projects will be managed for the Energy Department by the Office
of Fossil Energy’s National Energy Technology Laboratory, which
oversees the nation’s largest program in mercury control for existing
coal-fired power plants.
The selected projects are described below:
- URS Group, Inc. (Austin, Texas) will conduct a bench-scale
kinetic study of mercury reactions in wet flue gas desulfurization systems.
The objective is to determine the mechanisms and kinetics of the aqueous
reactions of mercury absorbed by these systems. A kinetic model to predict
mercury reactions will be developed for a range of potential designs
and operating conditions. The model can then be used to identify settings
that maximize mercury capture, minimize mercury re-emissions, and help
solidify mercury so that it leaves the system as a solid, rather than
liquid, byproduct. The kinetic study and model should enhance understanding
of the fate of oxidized mercury absorbed in wet flue gas desulfurization
systems, and will help remove a barrier to a technology that can efficiently
co-capture mercury. (Project duration: 2 years; Total award value:
$342,408)
- Purdue University (West Lafayette, Ind.) will develop and apply
new sensors for measuring the concentration of various mercury species
in flue gas. Researchers will develop a new optical sensor to measure
elemental and oxidized forms of mercury without extensive pretreatment.
A novel and compact laser source will be designed to faciliate measurement.
Approaches to eliminate or minimize interference from other gases will
also be devised. Purdue will also investigate the use of laser-induced
breakdown spectroscopy to measure total mercury in a system. Research
will focus on the resolution of interferences and the accurate measurement
of low levels (10 parts per billion) of mercury. The atomic mercury
sensor can be applied to in situ measurements of elemental mercury
in the actual coal-combustor exhaust stream. To assess the overall feasibility
of using sensors as continuous emission monitors, Purdue will team with
Texas A&M University to test the sensors using their bench-scale
combustion facilities. (Project duration: 3 years; Total award
value: $483,952)
- Gas Technology Institute (Des Plains, Ill.) will develop and
evaluate nanoscale sorbents for mercury capture from the warm fuel-gas
generated by coal-gasification systems. Investigators will conduct research
aimed at understanding the chemistry of mercury, as it relates to sorption,
on various metal-oxide materials. A fundamental understanding of these
interactions will serve as a basis for developing a sorbent for mercury
capture in coal-fired power generation systems under warm fuel-gas conditions
(pressures near 300 psi and temperatures from 300 oF
to 700 oF). Of primary interest is removing contaminants
from the gas while it is under these conditions to maintain the high
energy efficiencies of coal-gasification systems. In addition to mercury,
other trace metals, such as arsenic, may also be captured, which would
support development of a multi-pollutant control technology. (Project
duration: 2 years; Total award value: $304,169)
- Arizona Board of Regents (Tucson, Ariz.) will study sorption
mechanisms for mercury capture in warm post-gasification gas-cleanup
systems. Researchers will conduct bench-scale experimental and computational
tests to understand the interaction between certain trace metals, including
mercury, and a novel sorbent derived from paper-recycling wastes. Experiments
will not only investigate sorption at warm-gas cleanup conditions (300 ˚F
to 700 ˚F), but will also extend this range to temperatures
within the hot-gas cleanup range (above 1200 ˚F). The studies
will center around understanding the mechanisms that govern the sorption
of mercury and other metals, as well as the rate at which sorption occurs
as a function of temperature, sorbent flow rate, metal and gas composition,
and residence time. Computational methods will be directed toward predicting
stable metal speciation on sorbent substrates. Quantum-mechanical and
kinetic modeling will be used to correlate the experimental data, and
to extrapolate it to high pressures (300–1,000 psi). The University
of Arizona will team with Niksa Energy Associates for the derivation
and evaluation of kinetic models of mercury speciation. (Project duration:
3 years; Total award value: $558,594)
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