Flue Gas Cleaning Technology using Coal Ash Derived Absorbent

Abstract

Out of the studies of utilization of coal fly ash discharged from a coal-fired power station, an efficient absorbent for SO2 and NOx contained in the flue gas from the power station has been developed in the Department Research and Development at Hokkaido Electric Power Co., Inc. The absorbent is prepared by hydration of the mixture containing coal fly ash, lime and gypsum, followed by drying. A dry-type desulfurization facility using absorbent has been successfully operated in commercial scale since March 1991. By improving the hydration process, a more active absorbent was developed and named LILAC after the abbreviation of Lively Intensified Lime-Ash Compound. The LILAC absorbent is used in a semi-dry flue gas treatment system. The semi-dry system is being constructed at Huangdao Power Station in the People's Republic of China under the project “Green Aid Plan” of the Agency of Natural Resources and Energy, Ministry of International Trade and Industry. The utilization of the spent absorbent which is characterized by high abilities for ammonia absorption and solidifying sludge in water has also been studied in terms of recycling the industrial waste. The spent absorbent has registered name “Eco Sand”, and is ready for commercialization as deodorants for pets, shoes and refrigerator, and also as sludge solidification agent. © 1994, The Chemical Society of Japan. All rights reserved.