The objective of the proposed study is to develop and demonstrate pre-combustion mercury removal of raw coal by thermal treatment. A mercury removal efficiency improvement of at least 50% in the incoming coal will be achieved at less than $30,000/lb of mercury removed.

Key process steps in the WRI technology include treating the fuel at two selected temperature windows. In the first stage, the moisture in the fuel is driven-off; in the second stage, coal is heated by nearly inert gas resulting in significant removal of coal-bound mercury. The inert gas flow is an order of magnitude lower than the combustor flue gas and hence the stripping of mercury in the effluent streams becomes easier. The product coal is cooled and then directly fed into the boiler plant pulverizer.

A set of representative subbituminous, western bituminous and lignite coals will be evaluated. Project activities include bench-scale testing of eight coals followed by pilot-scale testing of three coals. In the bench-scale tests, the mercury removal will be characterized as a function of time and temperature. In the pilot scale testing, the effluent streams from the dryer and heater will be characterized. Two of these coals will be selected for further testing on a pilot pc-fired combustor to demonstrate the viability of removing more than the research target.

WRI will lead the research effort on the bench- and pilot-scale units and coordinate the project activities. WRI will be assisted by Etaa Energy, Inc. (EEI) in the design of the process development unit, analysis of the test data and preparation of the test reports. Energy and Environmental Research Center (EERC) will perform the pulverized coal combustion testing on a pilot plant using the product coal from WRI and measure the baseline and treated coal mercury emissions. Foster Wheeler Development Corporation (FWDC) will model the integrated performance of the coal thermal treatment unit with a pulverized coal-fired utility unit. Washington Group International (WGI) will perform an economic study of the commercial-scale application of the WRI process. The research program is expected to be completed in 30-months.

The proposed pre-combustion mercury removal process has shown very promising results in the preliminary tests. Mercury removal of 60-80% in the pre-combustion process will help improve the net (including the boiler island) mercury capture to 90% and above in low rank coals. A successful demonstration of the WRI process will lead to an accelerated deployment of commercial systems in subbituminous (such as PRB) and lignite (such as Fort Union ) coals. Co-benefits are also expected through significant reductions of NOx.

WRI, WY; Etaa Energy, NJ; FWDC, NJ; WGI, CO; Electric Power Research Institute, CA; Southern Company, AL; Basin Electric Power Cooperative, ND; North Dakota Industrial Commission, ND; Montana Dakota Utilities, ND; Detroit Edison, MI; and SaskPower, Canada.