Combustion of high-chlorine Illinois Basin coals in utility boilers

Many electric utilities that have not burned high-chlorine (>0.3%) Illinois Basin steam coals believe that chlorides in combustion gases contribute to increased boiler tube wastage rates. This concern regarding chlorine is not shared by traditional high-chlorine Illinois coal users. Nevertheless, it has limited the market for these coals with other potential customers. To resolve this predicament, the Illinois Coal Association formed a Chlorine subcommittee in December 1991. This presentation reviews the work performed by the subcommittee since its inception. The nature of chlorine in coal, a comparison of Illinois coal and UK coal qualities, utility experience with Illinois coal, and the effect of coal chlorine on corrosion of boiler furnace walls, superheater/reheater tubes, cold-end duct work, electrostatic precipitators, and flue gas desulfurization equipment is reviewed. The successful utilization of Illinois Basin coals in Midwestern utility boilers for many decades with no reported chloride-related problems demonstrates that high-chlorine Illinois steam coals can be burned without problems in electric utility boilers. The present consensus of leading corrosion engineers regarding the role of coal chlorine in fireside corrosion also supports this position.