APPARATUS FOR REMOVING SO3 COMPONENT IN EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To remove SO3 in an exhaust gas without causing a significant increase in the operation cost. SOLUTION: The concentration of SO3 in the exhaust gas is reduced by providing a sodium carbonate supplying device 20 for supplying sodium carbonate to the exhaust gas at the outlet of a boiler 1, and a SO3 -separating device 10 is provided for separating and removing the SO3 component from the exhaust gas at the inlet of a wet type desulfurization device 7. In the SO3 separating device 10, a shell and tube type heat exchanger is provided, and the exhaust gas and water to be supplied to the boiler are passed through the shell side and the tube side, respectively, so as to cool the temperature of the exhaust gas to a temperature lower than the dew point of gaseous H2 SO4 . With the lowering of the temperature of the exhaust gas, the SO3 component in the exhaust gas reacts with moisture in the exhaust gas and forms the gaseous H2 SO4 , and further, the formed H2 SO4 gas condenses and sticks on the surface of the tube. The SO3 component can be removed from the exhaust gas by washing liquid H2 SO4 stuck on the tube with water. Thereby, the consumption of sodium carbonate is markedly reduced and the increase in the cost for operating a plant is prevented.