| abstract |
(57) [Summary] [PROBLEMS] To remove SO 3 in flue gas without significantly increasing equipment cost and operation cost. SOLUTION: Boiler 1 before being treated by wet desulfurization device 7 SO 3 separation device 10 for separating and removing SO 3 components from flue gas Is provided. The SO 3 separation device is provided with a shell-and-tube type heat exchanger, and cools the flue gas to below the dew point of H 2 SO 4 gas by passing flue gas on the shell side and boiler feedwater on the tube side. The SO 3 component in the flue gas reacts with the moisture in the flue gas as the temperature decreases to form H 2 SO 4 gas, and the generated H 2 SO 4 gas condenses and adheres to the tube surface. By washing the liquid H 2 SO 4 attached to the tube surface with water, a part of the SO 3 component can be removed from the flue gas. Thereby, the size of the wet electrostatic precipitator 8 installed downstream of the wet desulfurization apparatus can be reduced, and the apparatus cost can be reduced as a whole. |