FLUE GAS TREATING METHOD

摘要

PROBLEM TO BE SOLVED: To miniaturize an electrostatic precipitator to make it low costed by a method wherein in that which eliminates dust and sulfur dioxide from a flue gas by using a dry electrostatic precipitator and a wet process line gypsum method desulphurizing equipment, a dust concentration of the flue gas coming out from the dry electrostatic precipitator to be introduced into an absorption tower, is set within a specific range. SOLUTION: An untreated flue gas A1 from a coal-fired boiler 1 is at first introduced into an air heater to heat air B to be supplied to the boiler 1. Then, the flue gas A1 is introduced into a heat recovery part 3a of a gas heater, and heat is recovered. After cooling, the flue gas is introduced into an electrostatic precipitator 4. Dust is removed from an inside of the flue gas A1, and a flue gas A2 of which a dust concentration is reduced to 100 mg/m<3> N to 500 mg/m<3> is exhausted. Then, the flue gas A2 is introduced into a desulfurizing equipment, and sulfur dioxide is removed by absorption. Besides, the dust is removed by being collected herein and thereafter, the flue gas is exhausted as a flue gas after treatment A3. The flue gas after treatment A3, after being heated with a reheating part 3b of the gas heater, is released from a stack.