Simultaneous reduction of SO{sub}2 and NO{sub}x emissions from fluidized bed combustors during petroleum coke combustion

摘要

A kind of petroleum coke was burnt in a circulating fluidized bed combustor (CFBC) and a bubbling fluidized bed combustor (BFBC). The effect of limestone batch feed for SO{sub}2 removal on NOx and N{sub}2O emissions was evaluated. NOx emissiondecreased with limestone feed but a difference in the pattern of the change in emissions was observed between NOx emission and SO emission. SO emission decreased immediately afier limestone feed when the limestone was fresh. whereas NOx emission decreased gradually. N{sub}2O emission decreased alter limestone feed to CFBC but it increased for BFBC.The bed material samples were taken from the CFBC before and after limestone feed and the catalytic activity of these bed materials for NOx formation and destruction was evaluated using a fixed bed reactor. Both bed materials were found to be strongcatalysts for NOx formation from fuel-N but the catalytic activity of the bed material sampled after the limestone feed was lower than that before limestone feed. A new explanation of NOx reduction after limestone feed was proposed.