IN-BED SULFUR REMOVAL DURING THE FLUIDIZED-BED COMBUSTION OF COAL IMPREGNATED WITH CALCIUM MAGNESIUM ACETATE

Sulfur removal during the fluidized bed combustion of coal has been carried out at temperatures of 960-1140 K. Coal impregnated with calcium magnesium acetate (CMA) is used as a sulfur sorbent. The amount of CMA actually loaded is larger for brown coal with a higher ion-exchange capacity. CMA shows no significant effect on the burn-off irrespective of the coal type and temperature. However, calcium impregnation is effective for in-bed sulfur removal. The efficiency depends on the coal type, probably the type of sulfur in the coal; a high sulfur retention is attained for Illinois No. 6 coal with a large proportion of pyritic sulfur in spite of low Ca/S ratios of around 0.5. In the coprocessing of bituminous coal with impregnated low-sulfur brown coal, the highly dispersed calcium in the brown coal captures effectively the sulfur evolved during the combustion of the bituminous coal.