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Show o Basic technical feasibility o Process performance: pyritic sulfur rejection and Btu recovery o Product handleability and storage o Economic considerations o Product acceptability o Environmental issues o Operational considerations o Ancillary considerations. The critical issue for the heptane process, from both the technical and economic viewpoints, Is selection of the equipment required for evaporation of heptane. The performance of this equipment Is measured by its specific energy requirements, the extent of agglomerate degradation, and the amount of trace heptane retained within the product agglomerates. The dryer systems under consideration Include: o Turbo rotary tray dryer o Vibrating fluidized-bed dryer o Bepex indirect dryer (microagglomerates only) Indirect dryers will be tested only with microagglomerates because of difficulties with asphalt adhering to the hot surfaces in the dryer. Initial tests at dryer vendor facilities have been completed with encouraging results. Design of an agglomerant recovery system is not seen as a major technical Issue since a suitable recovery system can be specified once the gas stream composition, flow rate, and applicable emissions regulations are defined. However, the capital and operating costs of such a system are highly dependent on these design parameters. The major technical issues requiring work for the diesel process are establishing the relationship between agglomerant dosage and resultant agglomerate recovery, product moisture, and other product physical properties. These relationships are being established at both the bench and pilot scales, as discussed in the section on unit operations testing. The initial results indicate that a high recovery of coal can be achieved at low binder dosages (3% feed coal basis) if more extensive dewatering equipment is used. Stringent environmental constraints are anticipated for future large process plants. As stipulated by current regulations, the upper limit for airborne volatile hydrocarbon emissions (VOC)--without special permit and in the most restrictive abatement zone-is 40 tjy; 100 t/y emissions are typically considered a large source of emissions. The major sources of emissions would be from the dryer recovery system and the fugitive stockpile emissions. At the conclusion of Phase 1 of the project, a recommendation will be made concerning the most attractive process option (diesel or heptane) to pursue at the proof-of-concept scale. Selection criteria will include technical feasibility, process performance, environmental acceptability, economic competitiveness, and product acceptability /handleability. Phase 2 will be devoted to engineering scale-up studies and optimization of the selected process In the proof-of-concept module. ACKNOWLEDGMENTS This work is primarily funded by the Department of Energy, Pittsburgh Energy Techndogy Center, Contract No. DE-AC22-89PC88879, and by the Electric Power Research Institute, RP 3118~1 . 10 |
