Mercury Program R&D Information Clearinghouse
In response to the need identified by the Canadian Electricity Association (CEA), the Energy & Environmental Research Center (EERC) is developing an information clearinghouse on global research and development activities in the areas of mercury monitoring and control. The primary program objective is to provide quarterly information updates (quarterly topical reports) pertinent to advancements in technologies relating to mercury measurement and control in North America and internationally. In addition, pertinent regulatory issues and research developments are being tracked and reported.

Mercury is an immediate concern for the Canadian and U.S. electric power industries because of impending regulation of mercury emissions. Canada has established a consultative process to develop Canada-wide standards (CWS) for mercury emissions from coal-fired electricity generation. A process is well under way to evaluate and discuss, in conjunction with a multistakeholder advisory group, options for achieving cost-effective reductions in mercury emissions.

Pilot-Scale Testing of Potential Mercury Control Technologies for TXU
This project is intended to identify and evaluate potential mercury control technologies at the pilot scale that show promise for application at plants burning Gulf Coast lignite, or a blend with subbituminous coal. Gulf Coast lignite is one of the most challenging coals in regard to mercury control because of its high mercury concentration and the high percentage of elemental mercury. 

Of all the mercury control options available to be deployed to meet pending mercury control regulations, ACI is considered to be among the most mature and, therefore, most readily available for commercial use in coal-fired power plants. However, very small amounts of carbon (generally considered to be <1% by volume) will render the fly ash unacceptable for commercial sale. One solution to this dilemma is to use a TOXECON™ system whereby AC is injected after an electrostatic precipitator (ESP), but prior to a fabric filter (FF), leaving the majority of the fly ash available for sale or further use. TXU’s Big Brown Station burns a Gulf Coast lignite- subbituminous blend and is equipped with a TOXECON™ configuration. Analysis of this Gulf Coast lignite blend shows a particularly high ratio of elemental mercury, providing a good test condition for evaluating ACI, as well as other possible control technologies.

Other options have also been shown by previous research to improve removal of mercury. For example, lowering the combustion temperature will often improve AC capacity. In addition, many forms of coal pretreatment have been found to have varying effects on mercury removal. Great River Energy (GRE) is developing a thermal treatment that has shown some success on North Dakota lignite to provide some mercury removal. The effectiveness of these approaches as well as new technologies need to be tested because of the unique challenges that Gulf Coast lignite presents.

Pilot and Full-Scale Demonstration of Advanced Mercury Control Technologies for Lignite-Fired Power Plants
The overall objective is to develop advanced innovative mercury control technologies to reduce mercury emissions from North Dakota lignite-fired power plants by 50% to 90% at costs of 1/2 to 3/4 of current estimated costs. The specific objectives are focused on determining the feasibility of the following technologies: Hg oxidation for increased Hg capture in wet and dry scrubbers, incorporation of additives and technologies that enhance Hg sorbent effectiveness in electrostatic precipitators and baghouses, use of amended silicates in lignite-derived flue gases for Hg capture, and use of Hg adsorbents within a baghouse. The proposed scope of work involves testing advanced sorbents and Hg oxidation agents for a range of Hg control options for ND lignite-fired power plants. The tasks include 1) Hg control enhancement for unscrubbed systems with an ESP-testing will be conducted with activated carbon injection, activated carbon injection with sorbent pretreatment and additives to increase reactivity, and amended silicate injection; 2) Hg oxidation upstream of wet and dry scrubbers-testing of oxidizing agents injected with coal, injected in flue gas, and sorbent enhancements; 3) cofiring with tire-derived fuel (TDF) for Hg oxidation-TDF has shown the potential to oxidize Hg0, and tests will be conducted to determine and better understand oxidation mechanisms at a lignite-fired power plant; 4) Hg control in the ADVANCED HYBRID™ (AH)-testing will be conducted for retrofit ESP applications with activated carbon and amended silicate sorbents injected upstream of the AH; and 5) field testing of sorbents - conduct short-term testing at a ND power plant using a slipstream baghouse to demonstrate Hg capture by sorbent injection.

Mercury Control with the Advanced Hybrid Particulate Collector
The Energy & Environmental Research Center at the University of North Dakota, Grand Forks, ND, will develop an advanced hybrid particulate collector (AHPC) that promises to remove 90 percent of all mercury emissions at a price lower than today's estimates. The AHPC combines the best features of electrostatic precipitators and baghouses in a configuration that boosts efficiency between particulate collection and dust disposal. By doing so, the problem ESPs generally have in collecting excessive fine particulates is solved as is re-collecting dust in conventional baghouses. The system is to be bench-scale batch tested so that new work is tied to earlier results; the AHPC would also undergo larger, pilot-scale testing on a coal-fired combustor. The technology could be retrofitted to ESP-equipped plants, installed in a new plant or applied to industrial boilers requiring mercury control. Partners are W.L. Gore & Associates, Elkton, MD, and the Otter Tail Power Company, Fergus Falls, MN, which will host field tests.

Public Abstract: The project team will include the Energy & Environmental Research Center (EERC) as the main contractor, W.L. Gore & Associates, Inc., as a technical and financial partner, and the Big Stone power station operated by the Otter Tail Power Company, which will host the field-testing portion of the research.

Since 1995, DOE has supported development of a new concept in particulate control, called the advanced hybrid particulate collector (AHPC). The AHPC combines the best features of electrostatic precipitators (ESPS) and baghouses in a unique configuration, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and re-collection of dust in conventional baghouses. The AHPC appears to have unique advantages for mercury control over baghouses or ESPs as an excellent gas-solid contactor.

The objective of the proposed three-task project is to demonstrate 90% total mercury control in the AHPC at a lower cost than current mercury control estimates. The approach includes bench-scale batch testing that ties the new work to previous results and links results with larger-scale pilot testing with real flue gas on a coal-fired combustion system, pilot-scale testing on a coal-fired combustion system with both a pulse-jet baghouse and an AHPC to prove or disprove the research hypotheses, and field-demonstration pilot-scale testing at a utility power plant to prove scaleup and demonstrate longer-term mercury control.

In April, 2003, the original Cooperative Agreement for the project was modified to expand the pilot-scale testing to include the application of the AHPC as a means of capturing mercury in flue gases that contain low levels of acid gases typical of spray dryer baghouse applications.  The testing will take place at UNDEERC's pilot-scale coal combustion facility in Grand Forks, ND, and includes refurbishing the existing pilot-scale spray dryer absorber (SDA) at that facility and evaluating the mercury removal performance of the combined SDA and AHPC devices when elemental mercury oxidation additives are used.   

The Cooperative Agreement was also modified to include field testing of a novel mercury sorbent technology developed by W. L. Gore & Associates, Inc.  The Gore technology consists of a proprietary baghouse insert downstream of the fabric filter that has shown a high potential to control Hg.  An existing pulse-jet baghouse will be mounted on a skid and equipped with a the novel Gore sorbent technology; the modified baghouse will then be installed downstream of an existing ESP device in an operating power plant in North Dakota.  Mercury removal achieved via the novel sorbent technology in the field will be compared to the mercury removal obtained in pilot-scale tests using the new technology in conjunction with both the AHPC and a pulse-jet baghouse.

This project, if successful, will demonstrate at the pilot-scale level a technology that would provide a cost-effective technique to accomplish both control of mercury emissions and, at the same time, greatly enhance fine particulate collection efficiency. The technology can be used to retrofit systems currently employing inefficient ESP technology as well as for new construction, thereby providing a solution to a large segment of the U.S. utility industry as well as other industries requiring mercury control.

Mercury Control Technologies for Electric Utilities Burning Lignite Coals
U.S. and Canadian power plants burning lignite have shown higher elemental mercury (Hg 0 ) emissions than plants burning bituminous coals. This form of Hg is much more difficult to remove. North Dakota produces over 30 million tons of lignite annually, and thousands of tons of lignite are fired by North Dakota power plants daily. The Energy & Environmental Research Center (EERC) is conducting a 3-year, 2-phase consortium project to develop and demonstrate Hg control technologies for utilities that burn lignite coal. The overall intent is to help maintain the viability of lignite-fired energy production by providing the local utilities lower-cost options for meeting future Hg regulations. Phase I objectives are to better understand Hg interactions with flue gas constituents, test a range of technologies targeted at removal of Hg 0 from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale.