Combustion Behavior and SO₂, NO_x Emissions of an Anthracite Coal in a Circulating Fluidized Bed

Combustion behavior and SO₂, NO_x emissions of anthracite coal in a circulating fluidized bed are reported in this paper. Experimental researches were done on a 1 MW_t circulating fluidized bed facility with a 0.31 m × 0.31 m cross section and 11.2 m height combustor. The anthracite coal with 6.28% volatile and 3.76% sulfur content burns steadily during the test. The bed was operated under different temperature, Ca/S ratio and excess air. A limestone containing 75% CaCO₃ and 15% MgCO₃ was used as the sulfur sorbent. Results show that the SO₂ emission varies with operating bed temperature and more than 90% sulfur capture efficiency can be reached while Ca/S is about 3. With Rosemount Analytical NGA2000, N₂O, NO and NO₂ were also measured in the test. It was found the majority content of NO_x was NO and the least was NO₂. Those NO_x emissions change highly with the excess air number.