MINIMIZATION OF CARBON LOSS IN COAL REBURNING

[摘要] This project develops Fuel-Flexible Reburning (FFR) technology that is an improved version of conventional reburning. In FFR solid fuel is partially gasified before injection into the reburning zone of a boiler. Partial gasification of the solid fuel improves efficiency of NO{sub x} reduction and decreases LOI by increasing fuel reactivity. Objectives of this project were to develop engineering and scientific information and know-how needed to improve the cost of reburning via increased efficiency and minimized LOI and move the FFR technology to the demonstration and commercialization stage. All project objectives and technical performance goals have been met, and competitive advantages of FFR have been demonstrated. The work included a combination of experimental and modeling studies designed to identify optimum process conditions, confirm the process mechanism and to estimate cost effectiveness of the FFR technology. Experimental results demonstrated that partial gasification of a solid fuel prior to injection into the reburning zone improved the efficiency of NO{sub x} reduction and decreased LOI. Several coals with different volatiles content were tested. Testing suggested that incremental increase in the efficiency of NO{sub x} reduction due to coal gasification was more significant for coals with low volatiles content. Up to 14% increase in the efficiency of NO{sub x} reduction in comparison with basic reburning was achieved with coal gasification. Tests also demonstrated that FFR improved efficiency of NO{sub x} reduction for renewable fuels with high fuel-N content. Modeling efforts focused on the development of the model describing reburning with gaseous gasification products. Modeling predicted that the composition of coal gasification products depended on temperature. Comparison of experimental results and modeling predictions suggested that the heterogeneous NO{sub x} reduction on the surface of char played important role. Economic analysis confirmed economic benefits of the FFR technology. Two options to gasify coal were considered: one included a common gasifier and another included a gasifier injector at each injection location. Economic analysis suggested that an FFR system with a common gasifier was more economic than a conventional reburning system and had NO{sub x} reduction cost similar to that of the major competing technology, LNB/SOFA system, for all economic scenarios.

[发布日期] 2002-09-10 [发布机构] General Electric Energy and Environmental Research Corporation (United States)

[关键词] Coal Gasification;Efficiency;Testing;Gasification;Minimization