FLUE GAS PURIFYING DEVICE

摘要

An object of the present invention is to provide a flue gas purifying device that can suppress leakage of ammonia and can efficiently decrease nitrogen oxides in flue gas. The object is achieved by including: an exhaust pipe that guides flue gas discharged from an internal combustion engine; a urea-water injecting unit that injects urea water into the exhaust pipe; a catalyst unit that includes a urea SCR catalyst that promotes a reaction between ammonia produced from injected urea water and nitrogen oxides and a support mechanism arranged inside of the exhaust pipe on a downstream side to a position where urea water is injected in a flow direction of the flue gas to support the urea SCR catalyst; an ammonia-concentration measuring unit that measures an ammonia concentration in flue gas at a measurement position in a region where the SCR catalyst is arranged; and an injection control unit that controls injection of urea water based on a measurement result acquired by the ammonia-concentration measuring unit.