URS Group and its test team will perform research to further develop the novel Mercury Control via Adsorption Process (MerCAP™). The general MerCAP™ concept is to place fixed structures into a flue gas stream to adsorb mercury and then periodically regenerate them and recover the captured mercury. EPRI has shown that gold-based sorbents can achieve high levels of mercury removal in scrubbed flue gases. URS is proposing tests at two power plants using gold MerCAP™, installed downstream of either a baghouse or wet scrubber, to evaluate mercury removal from flue gas over a period of 6 months. At Great River Energy’s Stanton Station, which burns North Dakota lignite, sorbent structures will be retrofitted into a single compartment in the Unit 10 baghouse enabling reaction with a 6 MWe equivalence of flue gas. At Southern Company Services’ Plant Yates, which burns Eastern bituminous coal, gold-coated plates will be configured as a mist eliminator (ME) located downstream of a 1 MWe pilot wet absorber , which receives flue gas from Unit 1.

Sorbent structure installation at each site will be followed by a 1-week intensive gas characterization period including use of semi-continuous emission monitors (SCEMs) to evaluate mercury removal from flue gas flowing across the fixed sorbents. The sorbents will then remain in service for approximately 6 months during which periodic sampling trips will be made to evaluate performance.

Additional tests will be performed at each site to evaluate the ability to thermally regenerate the gold-coated plates. These tests will be carried out using 40-acfm extraction probes, treating flue gas obtained immediately upstream of the pilot test units, and will evaluate the effect of multiple regeneration cycles on sorbent performance.

The results of this study will provide data required for assessing the feasibility and estimating the costs of a full-scale MerCAP™ process for flue gas mercury removal. It will provide information about optimal operating conditions for different flue gas conditions, the effectiveness of sorbent regeneration, and the ability of the gold sorbent to hold up to flue gas over an extended period. In addition, if successful, the novel approach of incorporating MerCAP™ structures in existing baghouse compartments will demonstrate a cost-effective means for achieving mercury control using existing baghouse technologies.