Rapid Analysis of Trace Elements in Coal Utilisation
AUTHOR: Lesley L. Sloss and Robert M. Davidson
DATE: June 2001
Trace element emissions from sources such as coal combustion are of concern with respect to potential health effects. This report reviews the most up to date information on the available technologies for rapid analysis of trace elements from coal combustion and gasification. The measurement of trace elements in coal, ash and gaseous emissions is currently a rapid growth area. There are currently no techniques for the rapid analysis of trace elements in coal and ash which can be used reliably and routinely, although techniques based on X-ray fluorescence and possibly mass spectroscopy show the most potential. Commercial multi-metal continuous emissions monitors (CEMs) suitable for coal-fired power plants are currently not available.
So far, legislation on emissions has been the main impetus behind the development of CEMs for trace elements. As a result the majority of on-line or rapid trace element analysers have been or are being developed primarily for measuring mercury emissions from waste incinerators. Conditions differ quite distinctly between coal-firect power plants and waste incinerators. The application of these systems to emissions from coal-fired power plants will not be as simple as emissions from coal combustion are generally at lower concentrations than those from incinerators. Also, acid gases and other flue gas components in emissions from coal combustion can cause interferences with many trace element measurement systems.
Work is being carried out at both international and national levels to evaluate CEM systems and to produce certification or validation schemes to guarantee the suitability of new systems for use on coal-fired power plants. It will be at least a few years before such schemes publish approval for CEM systems for monitoring metal emissions from coal-fired power plants, although CVAAS and CVAFS systems for mercury may well have such approval within a year or so. In the meantime, the suitability of CEMs for such applications will have to be carried out on a casey-by-case basis in conjunction with standard manual wet chemical measurement methods.