With the USEPA issuing a national regulation requiring high levels of mercury capture, the need exists for low-cost removal techniques that can be applied to coal-burning power plants. The injection of powdered activated carbon into the ductwork upstream of the particulate control device is the most developed technology for mercury capture. Alternative techniques for mercury capture also play a role because of the numerous configurations of air pollution control devices present within the power plants, as well as the many different coals and coal-blends being burned. These methods employ sorbents, catalysts, scrubber liquors, flue gas or coal additives, combustion modification, flue gas cooling, barrier discharges, and ultraviolet radiation for the removal of mercury from flue gas streams. The DOE Mercury Program was an enormous success, spurring continuing development, demonstration, and commercialization of many technologies for the capture of mercury.

An overview of current and alternative technologies for mercury capture from coal-derived flue gas will be provided. In addition, six methods for mercury control within coal-derived flue and fuel gases have been recently developed at NETL and will be discussed. The on-going research needs for mercury control include improved sorbent-flue gas contact, development of poison-resistant sorbents and catalysts, novel sorbent promoters, new scrubber additives for retention of mercury within wet FGD systems, concrete-friendly activated carbons, new continuous measurement methods, benign coal additives, byproducts research, and exploration of international markets.

Co-Authors:  Elliot Roth, Ken Ladwig and Ward Burgess, U.S. DOE NETL