IMI Interdisciplinary Mathematics InstituteCollege of Arts and Sciences

Employing Modeling to Reduce the Environmental Impacts of Coal-based Electricity Generation

  • Oct. 16, 2012
  • 2:30 p.m.
  • LeConte 312

Abstract

Coal is the most abundant fossil fuel, which is sufficient to supply current energy demands for up to 250 years. Due to coal’s abundance and projected use in the near future, decreasing coal combustion’s environmental impacts are of great importance. Emissions from coal combustion processes constitute a significant amount of the elemental mercury released into the atmosphere today. In this section of the presentation, fate of mercury in coal-fired power plants and various technologies to reduce mercury emissions will be discussed. Activated carbon, when injected into the gas stream of coal-fired boilers, is effective in capturing both elemental and oxidized mercury through adsorption processes. However, the mechanism by which mercury adsorbs on activated carbon is not exactly known and its understanding is crucial to the design and fabrication of effective capture technologies for mercury. The objective of this study is to apply theoretical-based cluster modeling to examine the possible binding mechanism of mercury on activated carbon. In addition, understanding mercury speciation during combustion and how the transformations occur between different forms is essential to developing an effective control mechanism for removing mercury from flue gas. In this study, homogeneous oxidation of mercury via chlorine is examined experimentally in a simulated flue gas environment. A new kinetic model to predict the extent of homogeneous mercury oxidation via chlorine that can validate the experimental results will be presented.

Carbon dioxide emissions from fossil fuel energy generation has gained great attention recently due to the concerns with global warming. The second part of the presentation focuses on oxy-combustion of coal, which is a new technology that is currently being developed for carbon capture and sequestration. In an oxy-fired coal power plant, coal is burned in an oxygen-rich environment and the flue gas is recycled back to the boiler, which in the end produces a highly concentrated carbon dioxide stream that can be captured at relatively low-cost and subsequently compressed and sequestered. For the existing conventional power plants to be retrofitted, the operational and environmental impacts of oxy-combustion need to be evaluated. As research in this area is beginning to grow, the fundamental understanding of pollutant formation remains to be elucidated and before developing removal technologies, one needs to understand the speciation and behavior of these pollutants under oxy-fired conditions. This research will be a comprehensive investigation of pollutant formation during oxy-fuel combustion at a fundamental level combining bench-scale experiments, kinetic modeling and molecular modeling.

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