DIOXIN REGENERATION PREVENTING DESUPERHEATER AND SYSTEM AND METHOD FOR TREATING COMBUSTION EXHAUST GAS USING IT

PROBLEM TO BE SOLVED: To prevent a high-temperature gas which is produced when dioxins are decomposed at a high temperature and contains trace amounts of dioxins and their precursors from being regenerated into dioxins in desuperheating stage. SOLUTION: The relatively high-concentration dioxins generated in the process of incineration in an incinerator 1 are led to a dioxin decomposing device through the inlet 7 of the device and heated to >=700 deg.C for decomposition. The gas produced as a result of decomposition still contains an ultramicro amount of dioxins of about 0.01 ng/Nm3 and their precursors and is led to the inlet 5 of a desuperheater. The high-temperature combustion gas flowing in the desuperheater is led to a chimney 4 through the outlet 6 of the desuperheater in a state where dioxins are not synthesized while the temperature of the gas becomes lower as the gas gives latent heat of vaporization to a liquid refrigerant and discharged into the atmosphere. The temperature at the outlet 6 of the desuperheater is fixed in such a way that a detector 18 detects the gas temperature at the outlet 6 and the flow rate of the liquid refrigerant supplied to a liquid refrigerant atomizing nozzle 9 is controlled by controlling the valve travel of a flow control valve 2 by transmitting the detected temperature to the valve 21.