EXHAUST GAS DESULFURIZING APPARATUS

PURPOSE:To provide a rational and compact exhaust gas desulfurizing apparatus by simplifying a bypass air passage system for waste gas. CONSTITUTION:A bypass duct 22 of an absorption tower 8 is used to prevent high temperature gas from flowing into the absorption tower 8 upon failures of the absorption tower 8 and a BUF 7, and is used to avoid the fear of corrosion of a flue because outlet gas from the absorption tower 8 is prevented from being re-heated upon starting of a boiler. Since the bypass duct 22 is not used upon ordinary operation, the foregoing trouble is sufficiently dealt with by setting the cross section area of the bypass duct 22 to be smaller than that of the flue connecting between the outlet of a dust collector 3 and the absorption tower 8. Further, the BUF 7 is automatically interrupted when pressure of the IDF 6 oultet duct exceeds set pressure, and a purification apparatus including the absorption tower 8 is brought into trip. Further, the IDF 6 is generally automatically interrupted when furnace pressure in the boiler 1 exceeds the set pressure, and a boiler fuel is also interrupted into a boiler trip. Provision of means for protection in trouble may eliminate the use of the bypass duct 22.