METHOD AND SYSTEM FOR DESULFURIZING EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To provide a stack gas desulfurizing method capable of effectively removing NS compd. exerting undesirable influence to desulfurizing performance and also capable of removing heavy metals, especially manganese, in desulfurized waste water. SOLUTION: In the exhaust gas desulfurizing method using wet lime method for treating the waste gas containing sulfur oxide and nitrogen oxide, an oxidizing stage in which total quantity or a part of filtrate is adjusted to pH 3-4 and an oxidizing agent is added after discharging a part of absorbing slurry at a desulfurizing stage, adding a heavy metal chelate agent and separating gypsum, a neutralizing stage in which an alkali agent is added to the mixture to adjust the mixture to pH 7-9.5 and a solid-liq. separating stage for subjecting the neutralized adjusted liq. to solid-liq. separation are provided and the exhaust gas desulfurizing system using the method is provided.