W. S. Hinton & Associates
Research and Consulting Engineers

We have considerable experience in mercury control processes including process evaluation, developmental research, speciated mercury testing, and mercury data analysis.  

For many utilities, mercury control has become a major issue for coal-fired plants, and in fact mercury control has moved to the forefront of the long-term environmental controls planning for some utilities.  Mercury control is a complicated issue due to the very low levels of mercury present in flue gas, and the difficulties in accurately measuring the absolute level of mercury, especially in terms of the mercury species that are present.  The mercury speciation is an important factor with all mercury control technologies.

A number of technologies are available for mercury control, each with its own specific capabilities and problems.   Technologies that either capture mercury, or impact mercury speciation,  include;  SCR (for mercury oxidation), wet scrubbers, dry and wet ESPs, activated carbon injection, sorbent injection, dry scrubbers, and other novel technologies.  The myriad  technologies available for capturing mercury, along with their highly variable performance and applicability, make choosing the right technology for a particular application very difficult. 

 In particular, we have a great deal of experience related to the oxidation of mercury using SCR.  SCR catalysts are known to oxidize mercury, but the actual oxidation efficiency is dependent on many factors including the SCR operating condition (flow rate, temperature, deNOx level, etc.) as well as the catalyst formulation, and especially the flue gas composition.  Flue gas levels of chlorine and bromine, in particular, strongly influence the level of mercury oxidation that occurs across SCRs.  We have been involved with several SCR-related projects associated with mercury oxidation and capture at the Mercury Research Center, located at Gulf Power’s Plant Crist, in Pensacola, Florida.  These projects have made significant headway in evaluating the mercury oxidation performance of a number of catalysts with respect to various flue gas parameters, and have evaluated the resulting capture efficiency of mercury across a cold-side ESP, and wet scrubber.  Other similar work has examined the relative mercury oxidation performance of new, aged, and regenerated catalysts.