Exhaust gas treatment system and method

Abstract

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 SO2·SO3 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 SO2 (sulfur dioxide) in the denitrified exhaust gas (12A) into SO3 (sulfur trioxide); a heat exchanger (16) that is provided in the flue (13) on the wake side of the SO2·SO3 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 SO2 contained in an exhaust gas into SO3; subjecting the SO3-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.

Description

technical field [0001] The invention relates to a waste gas treatment device and method. Background technique [0002] In thermal power plants and the like, nitrogen oxides (NOx), sulfur oxides (SOx), coal dust, and the like generated with the combustion of fossil fuels are contained in exhaust smoke (exhaust gas). These NOx, SOx, coal dust, etc. cause air pollution, so in thermal power plants with coal-fired boilers, etc., install exhaust gas treatment equipment with denitrification equipment for removing NOx and exhaust gas desulfurization equipment for removing SOx . [0003] Here, the wet limestone-gypsum method is dominant in the flue gas desulfurization device, in which the limestone slurry is sprayed from the nozzle to make it contact with the waste gas gas-liquid with high reliability, and is often used as a A spray method of spraying limestone slurry in a tower is adopted (Patent Document 1). [0004] Previous technical literature [0005] patent documents [0...

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Problems solved by technology

[0008] However, although the desulfurization device of the wet system has excellent desulfurization performance, it has a problem of increasing water consumption.

[0009] With regard to desulfurization devices of a dry type other than a wet type, it has been proposed, for example, to remove SO using activated coke 2 method, but there are problems of insufficient performance or energy loss and large utility

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