Experimental Research and Analysis on Self-Desulfuration Efficiency of Coal in Circulating Fluidized Combustor

The SO₂ emission is less than the theoretical value without additional limestone put in a circulating fluidized bed (CFB) combustor because of the self-desulfurization ability of calcium-based minerals in coal ash. The modeling and experiment on limestone sulfur retention should consider the self-desulfurization of coal ash. The self-desulfurization performance of some coal (18 kinds of coal) are researched and analyzed by the 1MW_th CFB combustor in order to evaluate the limestone desulfurization performance. The experimental results show that the self-desulfurization efficiency decreases with the temperature increasing. The self-desulfurization difference exits between different types of coal and has effect on the sulfur retention with additional limestone. Through the experimental result of 18 coals, simple equations of the self-desulfurization efficiency based on the total sulfur and the combustible sulfur are proposed. The self-desulfurization efficiency based on the combustible sulfur is between 40–40%. For high incombustible sulfur fraction in coal, the self-desulfurization efficiency and the sulfur retention of limestone is very high.