LIGNITE FUEL ENHANCEMENT

摘要

Project Goal and Objectives Our goal and objective is to significantly enhance the value of lignite as a fuel in electricalgeneration power plants within the next 5 years. Although current lignite power plants aredesigned to burn high-moisture coals (about 40%), a reduction in moisture content of 5 to15 percentage points (about one quarter of the moisture content in the coal) will result insignificant improvements.All fossil steam plants reject large quantities of heat in the cooling water used to condensesteam. Engineering studies at Great River Energy (GRE) Coal Creek Station show thatthis waste heat could be used to lower the moisture content of the coal by at least 10percentage points (or one quarter of the moisture in the coal). Reducing the moisturecontent of the coal will translate into the following benefits for the U.S.:? Increasing the net generating capacity of units that burn high-moisture coal.? Increasing the new energy supply of units that burn high-moisture coal.? Increasing the cost-effectiveness of the nation’s electrical generation industry.? Improving the environment by reducing emissions from coal-fired plants.? Increasing the value of the nation’s lignite reserves.The cost benefits from improved plant performance, reduced emissions, and increasedavailability far out weigh the cost of drying the fuel. This work represents a potentiallandmark advance of fossil-steam plant performance improvement, emissions reductionand plant availability and is also applicable to Powder River Basin sub bituminous andbiomass high moisture fuels as well.Efficiency, Environmental, and Economic Improvements 3Existing technology is such that lignite and PRB power plants mechanically feed the asreceivedcoal into pulverizing mills and then blow it into the combustion chamber. ThisLignite Fuel Enhancement Project proposes to demonstrate coal drying technology whichwill incrementally reduce the moisture content by about 25% (I.e., from about 40% toabout 30%). Analyses and field-testing show that the removal of about one-quarter of thecoal moisture results in:? A substantial (about 5%) improvement in overall performance? About a 25% reduction in mass emissions of SO2 and a 7% reduction in otherpollutants such as CO2 , NOx, ash and mercury ? A conservative savings of about $3M per year for one 546MW unit at Coal CreekStation? A potential economic savings of about $84M per year (15,000 MW of U.S. lignitepower plants)? A potential economic savings of about $840M per year (150,000 MW of U.S. PRBsub bituminous power plants)The economic savings quoted above are believed to be conservative because they do notinclude savings due to increased availability, capacity factor, pre combustion mineralremoval and post combustion emission reductions other than SO2.Applied to 15 GW of lignite generation and 150 GW of PRB coal generation and assuminga future value for carbon at $10/ton (or $2.725/ton of CO2), the proposed coal dryingtechnology offers a total potential saving due to CO2 reduction is nearly $3 billion peryear. Even a modest penetration of the proposed technology into this generation base couldultimately return a very large cost saving due solely to reduction of CO2 emissions.MethodologyThe benefits of reduced-moisture-content lignite will be demonstrated at the GRE CoalCreek Station in Underwood, North Dakota. A phased approach will be used. In the firstphase, a 2T pilot dryer will be tested. Types of dryers (fixed vs. vibratory), segregation ofmaterials, quantify magnetic & air separation benefits, and optimize operational concernsas we scale-up to a 75T/hr prototype. The second phase will be the prototype dryermodule, which will be fully integrated into one of the 546 MW units at the Coal CreekStation. Following successful demonstration of that dryer and the performanceimprovements as a result of it, GRE will design, construct, and perform full-scale longtermoperational testing of a full suite of dryer modules for full operation of the unit onincrementally dried coal, Phase 3. Six will be needed for full load.Sponsoring OrganizationGRE is the principal project sponsor. Other collaborating organizations include FalkirkMining and Couteau Properties, EPRI, Lehigh University, NETL, NDIC, and BarrEngineering.