METHOD FOR DECHLORINATING COMBUSTION EXHAUST GAS AND DECHLORINATION DEVICE

PROBLEM TO BE SOLVED: To treat a combustion exhaust gas whose specified target concentration of hydrogen chloride is met by treating the combustion exhaust gas originating from a combustion furnace through dechlorination process with slaked lime or quick lime within the specified range of temperature. SOLUTION: Hydrogen chloride contained in an exhaust gas originating from a combustion furnace 1 is treated (dechlorinated) at a device filled with an arranged slaked lime (dechlorination device) at 300-580 deg.C so that the hydrogen chloride concentration is, for example, 45 ppm at 550 deg.C. Next, the exhaust gas is used for producing steam in a boiler 3 and this steam is supplied at a higher temperature than a conventional type of steam at 250 deg.C or less for power generation. In this case, the temperature is detected using a temperature sensor 4 in piping before the dechlorination device 2. When it is forecast that the sensor 4 temperature exceeds 580 deg.C due to a change in the sensing performance over time of the temperature sensor 4. A fuel supply control device 5 or a cooling water loading control device 6 is controlled so that the temperature of the sensor 4 does not exceed 580 deg.C. Thus it is possible to treat the exhaust gas whose target treatment concentration of hydrogen chloride of 50 ppm or less is met.