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Show INTRODUCTION Significant advances in coal cleaning have been made since the promulgation of the New Source Performance Standards (NSPS) of the Clean Air Act. Several advanced coal preparation processes are under development with funding from the U. S. Department of Energy and have the potential to allow the low-cost production of deeply beneficiated coals. Economic removal of between 15% and 90% of the mineral matter and between 80% and 90% of the pyr i tic sulfur in the raw coals may be poss ible. Such fuels are be ing developed not only for acid rain control but also for oil and gas back out from the existing boiler population. I t is expected that these fuels will be fired in oil- and gas-designed utility and industrial boilers and in preNSPS coal-fired utility boilers. To achieve the level of coal cleaning necessary to meet these goals, not only is the fuel quali ty modified but also the fuel form. Many of the advanced coal-cleaning processes require that the coal be ground to very fine sizes, i. e., at least 80% finer than 100 mesh and possibly finer than 80% through 325 mesh. In addition, many of the processes involve water, and the product is in the form of a slurry or a filter cake. The option exists to dry and process these products into powdered or pelletized fuels. Because of the lack of practical (full-scale) experience with highly processed fuels, such as deeply beneficiated coals and coal-water mixtures (CWM) , the utility and industrial boiler designers and operators are reluctant to fire them. Potential problem areas are fuel transport, handling and storage, combustibility, ash deposition (slagging and fouling), corrosion (high- and low-temperature), erosion, and emissions (gaseous and particulate) . To gain the acceptance of the user communi ty, a detailed analysis of the combustion properties of deeply beneficiated fuels, prior to full-scale production, is warranted. Such evaluations will serve to screen potential coals through the various cleaning processes and to allow identification of promiSing processes for commercialization. TEST PROGRAM A multilevel evaluation of the combustion performance of beneficiated coalbased fuels (BCF) is under way at the DOE's Pittsburgh Energy Technology Center: Level 1: Level 2: Level 3: Level ~: Standard Laboratory Analyses Bench-Scale Combustion Experiments Laboratory-Scale Combustion Experiments Pilot-Scale Combustion Experiments Level 1 efforts represent a typical approach to fuel characterization and consist of conventional laboratory analyses, particularly those described by standard methods (e.g., proximate and ultimate analyses, and ash fusibility). These conventional analyses will be augmented by other specialized tests, when required, such as measurement of particle surface area and porosity, leachable alkali, and slag viscosity_ Level 2 experiments consist of a number of specialized bench-scale procedures based on the use of a thermogravimetric analyzer (TGA). General procedures have been established |
