A sample acquisition concept for element detection in coal-fired power plant emissions via laser-induced breakdown spectroscopy

A design course sequence in the electrical engineering curriculum at Western Kentucky University is being employed to introduce several EE students to environmental issues by way of a real-world project of interest to the electric power community. The project goal is to address the need to detect and ultimately quantify the presence of mercury in power plant flue gas emissions. An optical technique known as Laser Induced Breakdown Spectroscopy (LIBS) is being evaluated for this purpose. LIBS makes use of a tightly-focused laser beam to spark, or ablate, a chemical sample in either solid, liquid, or gaseous form. The emitted light is then analyzed by a spectrometer to determine constituent elements. Whereas the technique involved in LIBS has been demonstrated time and again in a variety of applications, the challenge at hand is the integration of the technique to on-line power plant flue gas analysis. Current work involves a sample acquisition means by which flue gas might be collected on a substrate, then subjected to LIBS analysis. Challenges to be addressed include exposing the substrate to the appropriate environment and ensuring sufficient elemental concentration for detection. Initial LIBS results with coal and coal ash, in lieu of flue gas, will be presented. Furthermore, pedagogical issues, such as employing a juniorlevel design course to perform real-world engineering on environmental and other problems, will be discussed.