CEM - Abstract

Abstract Information :

Mercury (Hg) is a toxic heavy metal naturally present in our environment which is of growing global concern. The UNEP Minamata Convention on Mercury has been signed and ratified by more than 200 countries since 2013. The objective of the Convention is to protect human health and the environment from anthropogenic emissions and releases of mercury. Coal burning is one of the most significant anthropogenic sources of mercury emissions to the atmosphere making more than 85 % of these emissions.

According to the Industrial Emissions Directive (IED, 2010/75/EU) a regular exchange of information between the EU member states on Best Available Techniques (BAT) is required. Within the revision of a Best Available Techniques Reference (BREF) Document the pollutant concentrations from representative plants are taken into account in order to determine Best Available Technology Associated Emission Levels (BAT-AEL). By national legislation the European member states have to ensure that the implementation at the affected plants takes place within four years after publication.

The revised BREF Document for large combustion plants (BREF LCP) has recently been adopted. The included BAT associated emission levels for total mercury of 1 - 4 µg/mN3 for hard coal-fired power plants and 1 - 7 µg/mN3 for lignite-fired power plants as yearly average are considerably below the current European emission limit values. Today most European coal-fired power plants do not apply any Hg specific reduction methods but benefit from the Hg capture at the existing stages of the flue gas cleaning system. In order to comply with the new emission levels Hg specific reduction measures have to be applied such as for example fuel pretreatment, carbon sorbent injection or boiler bromine addition.

I will demonstrate the versatile applications of continuous measuring mercury analyzers (Hg AMS) for continuous emission monitoring as well as for optimization of mercury specific reduction measures. In this context the determination of the ratio of the mercury species present in the flue gas (elemental mercury Hg0 and ionic mercury Hgn+) at different stages of the flue gas cleaning system is especially of interest. I discuss the advantages of continuous Hg measurement in comparison with discontinuous methods such as long-term sampling and the standard reference method according to EN 13211. I present practical examples using Hg AMS allowing speciation of Hg0 and Hgn+ for continuous Hg measurements at different stages of the flue gas cleaning system.