(103c) Specification Metrics for Activated Carbons Used for Mercury Control

Chemicals typically consumed in air pollution control applications like ammonia for selective catalytic reduction or lime and limestone for scrubbers can be specified fairly simply with small differences in the resulting pollution reduction performance. Heterogeneous activated carbons used for flue gas mercury control, however, are not discrete chemicals, as such, and there can be great differences in their demonstrated performance depending on many material-related factors.

Unfortunately, good correlations between traditional activated carbon specification metrics and mercury performance have proven elusive so far. There has not yet been a ?mercury number? developed to gage relative mercury performance, like the molasses number used to gage molasses decolorization efficiency, for example.

This presentation will review the effects that traditional metrics like particle size, surface area, and density have in this application and posit new characteristics such as bromine level, thermal conductivity, electrostatic properties, and concrete-friendliness which can have major impacts on the desirability of particular carbons in particular situations. A number of new metrics will be proposed for consideration in specifying activated carbons for this application.