Patent ID: 7507381

Claim:
An exhaust gas processing device comprising: an air preheater for preheating air for combustion in a combustion device by using an exhaust gas emitted from the combustion device; a gas-gas heater heat recovery device comprising heat transfer tubes for recovering the heat of the exhaust gas at a outlet of the air preheater to a heat medium; a dust collector for collecting dust in the exhaust gas at an outlet of the gas-gas heater heat recovery device; a wet-type desulfurization device for removing sulfur oxide in the exhaust gas at an outlet of the dust collector; a gas-gas heater re-heater comprising heat transfer tubes for heating the exhaust gas at an outlet of the wet-type desulfurization device by using the heat medium supplied from said gas-gas heater heat recovery device; at least some of the heat transfer tubes of the gas-gas heater are composed of fin-equipped heat transfer tubes, and the fin pitch of the heat transfer tubes of the gas-gas heater heat recovery device being set at 7.25 to 10.16 mm, and the fin pitch of the heat transfer tubes of the gas-gas heater re-heater being set at 6.35 to 8.47 mm; being arranged in that order from an upstream side to a downstream side of an exhaust gas duct of the combustion device; and a heat medium circulation line for connecting heat transfer tubes provided in each of the gas-gas heater heat recovery device and the gas-gas heater re-heater and for circulating the heat medium through the heat transfer tubes, wherein the heat transfer tubes of the gas-gas heater heat recovery device are squarely arranged in the gas flow direction in such a manner that the inter-tube flow rate, which is the flow rate of the exhaust gas between the heat transfer tubes adjacent in the direction orthogonal to the gas flow direction, can be less than 10 m/s.