TY - JOUR
T1 - Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part II. Lime Sludge Characterization and Mercury Re-emission
AU - Dastgheib, Seyed Abolfazl
AU - Salih, Hafiz Hussein Mohamed
AU - Li, Jiaxing
AU - Patterson, Craig
N1 - Funding Information:
The U.S. Environmental Protection Agency Office of Research and Development, through its Pathfinder Innovation Program, funded and collaborated in the research described herein. This work has been subjected to the Agency’s administrative review and has been approved for external publication. Any opinions expressed in this article are those of the authors and do not necessarily reflect the views of the Agency; therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use. The authors thank Justin Mock from the Illinois State Geological Survey (University of Illinois) for his assistance in performing the reactivity experiments for the lime sludge and limestone samples.
Publisher Copyright:
© 2018 American Chemical Society.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2018/6/21
Y1 - 2018/6/21
N2 - The feasibility of utilizing lime sludge in the flue gas desulfurization process of coal-fired power plants was evaluated through laboratory-scale studies. Eight lime sludge samples, collected from various water treatment plants, and a high-purity limestone sample were extensively characterized and tested for their ability to capture SO2 from a simulated flue gas, while investigating the mercury re-emission profiles during the scrubbing process. The reactivity of lime sludge samples for acid neutralization was considerably higher than the reactivity of the tested limestone sample. At doses less than that of the limestone sample, the lime sludge materials reduced the SO2 concentration from 2,000 to <0.5 ppm. The residual lime, greater surface area, and more accessible pores in the lime sludge samples were the major factors contributing to their higher reactivity. Concentrations of several elements, including B, Mg, Mn, Fe, Cu, Zn, As, Sr, and Ba, in some of the tested lime sludge samples were considerably higher than those of the elements in the limestone. However, no significant leaching of these elements into the scrubber solutions was observed. To investigate mercury re-emission during the scrubbing process, ionic mercury was introduced into the simulated slurry and mercury re-emission was monitored continuously. Results showed that compared with the limestone sample, the lime sludge samples tested had lower or similar cumulative mercury re-emissions. However, different lime sludge samples showed different emission profiles. No conclusive correlation between the composition or trace element content of the lime sludge samples and their mercury re-emission could be identified. This result was likely due to the oxidative condition of the scrubbing process, which prohibited the reducing species from transforming the ionic mercury into elemental mercury.
AB - The feasibility of utilizing lime sludge in the flue gas desulfurization process of coal-fired power plants was evaluated through laboratory-scale studies. Eight lime sludge samples, collected from various water treatment plants, and a high-purity limestone sample were extensively characterized and tested for their ability to capture SO2 from a simulated flue gas, while investigating the mercury re-emission profiles during the scrubbing process. The reactivity of lime sludge samples for acid neutralization was considerably higher than the reactivity of the tested limestone sample. At doses less than that of the limestone sample, the lime sludge materials reduced the SO2 concentration from 2,000 to <0.5 ppm. The residual lime, greater surface area, and more accessible pores in the lime sludge samples were the major factors contributing to their higher reactivity. Concentrations of several elements, including B, Mg, Mn, Fe, Cu, Zn, As, Sr, and Ba, in some of the tested lime sludge samples were considerably higher than those of the elements in the limestone. However, no significant leaching of these elements into the scrubber solutions was observed. To investigate mercury re-emission during the scrubbing process, ionic mercury was introduced into the simulated slurry and mercury re-emission was monitored continuously. Results showed that compared with the limestone sample, the lime sludge samples tested had lower or similar cumulative mercury re-emissions. However, different lime sludge samples showed different emission profiles. No conclusive correlation between the composition or trace element content of the lime sludge samples and their mercury re-emission could be identified. This result was likely due to the oxidative condition of the scrubbing process, which prohibited the reducing species from transforming the ionic mercury into elemental mercury.
KW - flue gas desulfurization, limestone, lime sludge, mercury reemission
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U2 - 10.1021/acs.energyfuels.8b00824
DO - 10.1021/acs.energyfuels.8b00824
M3 - Article
SN - 0887-0624
VL - 32
SP - 6634
EP - 6640
JO - Energy & Fuels
JF - Energy & Fuels
IS - 6
ER -