CYANIDE EMISSIONS IN COAL FIRED POWER STATIONS IN SPAIN

摘要

Cyanides are a group of compounds with high toxicity and they are important precursors of nitrogen oxides (NO_x) emissions in coal fired power stations. The nitrogen contained in coal originates in the release of cyanide compounds during the pyrolysis due to the reducing conditions in the boiler. When the oxygen concentration is increased, these compounds are oxidized and finally they are emitted as NO_x. The study of these compounds could improve our knowledge about the combustion process in coal fired power stations. In this study, the cyanide concentration of the flue gases emitted by five pulverized coal fired power plants and one with a fluidized pressurized boiler were measured. The levels found in the conventional power plants were similar in all of them. The plant with the tluidized pressurized system presents the greatest cyanide levels in their emissions. Relations between cyanide, oxygen and nitrogen oxides concentrations in stack were studied, but no direct relations were found.