No abstract

The limestone injection multistage burner (LIMB) process is currently being developed at the Environmental Protection Agency as a low-cost, retrofittable technology for controlling oxides of sulfur and nitrogen from coal-burning utility boilers. The most effective commercial, calcium-based sorbent for this process is calcium hydroxide [Ca(OH)2], which achieves sulfur dioxide (S02) removals of around 50% at a calcium-to-sulfur ratio of 2. Additions of calcium lignosulfonate up to 1.5 mass % dry product, introduced with the water of hydration, increase the S02 capture of the resulting Ca(OH)2 to 60%. This is achieved through particle size reduction in the modified hydroxides. The principal mechanism of size reduction appears to be through deagglomeration of the Ca(OH)2 crystals, while a secondary benefit may be derived from crystal size reduction.