EXHAUST GAS TREATMENT SYSTEM AND METHOD

摘要

This exhaust gas treatment system has: a denitrification device (14) that is provided in a flue (13) through which an exhaust gas (12) from a boiler (11) is discharged and that removes nitrogen oxides from the exhaust gas (12); an SO·SO conversion catalyst unit (15) that is provided in the flue (13) on the wake side of the denitrification device (14) and that has a conversion catalyst which converts SO (sulfur dioxide) in the denitrified exhaust gas (12A) into SO(sulfur trioxide); a heat exchanger (16) that is provided in the flue (13) on the wake side of the SO·SO conversion catalyst unit (15) and that conducts heat exchange between the exhaust gas (12B) which has passed through the catalyst and air (20) to lower the temperature of the exhaust gas (12B) to a sulfuric acid dew point or lower and that makes dust and soot adhere to the surfaces of sulfuric acid droplets contained in the exhaust gas the temperature of which has been lowered to a sulfuric acid dew point or lower in the heat exchanger (16); and a dust collector (17) that collets not only the dust and soot covered sulfuric acid but also dust and soot contained in the exhaust gas (12C). In the exhaust gas treatment system the desulfurization of an exhaust gas is attained by: catalytically converting SO contained in an exhaust gas into SO; subjecting the SO containing exhaust gas to heat exchange with air in a heat exchanger to lower the temperature of the exhaust gas to a sulfuric acid dew point or lower; making dust and soot adhere to the surfaces of sulfuric acid droplets contained in the exhaust gas; and collecting the dust and soot covered sulfuric acid together with dust and soot by a dust collector.