COMBUSTION OF COAL-WASHING PLANT RESIDUES AND HIGH-SULFUR COALS IN UTILITY-TYPE CFB BOILERS

摘要

Two specially promising applications of the CFB boiler technology are discussed (with examples of utility-type projects): 1) Coal-washing-plant residues (high-ash middlings, and the very fine coal residues, or "schlamms", transported by the washing plant water).. E. Huchet 125 MWe currently operates with schlamms directly injected into the furnace as a 33% water coal-water slurry, 2) High-sulfur coals. Teruel 150 MWe is designed for 90% desulfurization of a very high sulfur lignite (4.5% S, ie 5.2 mg/kJ). Provence 250 MWe has a 400 mg/Nm{sup}3 limit on SO{sub}2 emissions with a 2.5 mg S/kJ coal. Efficient bed temperature control (achieved through the External Heat Exchanger) is essential for high desulfurization performances. Such developments are certainly of interest to many countries which want to protect their environment at a reasonable cost, as well as to make the best use of their low-grade fuel resources.