| 摘要 |
PURPOSE:To prevent the lowering of a rate of denitration after regeneration by a method wherein a mol ratio of NH3 to NOx in combustion exhaust gas containing NOx and SOx being introduced to a catalyst bed after regeneration is increased to a specified range for temporarily. CONSTITUTION:NH3 gas, a reductant, is mixed with combustion exhaust gas containing NOx and SOx, and the mixture is passed through a denitrating catalyst bed under a condition that a mol ratio of NH3 to NOx is 0.8-1.2 and temperature is 150-300 deg.C, and denitrated. When the activity of the catalyst bed lowers, the catalyst bed is heated at 350-400 deg.C, and regenerated. When introducing exhaust gas to the catalyst bed after regeneration, the mol ratio of NH3 to NOx is increased to a range of 1.5-4. Temperature is lowered to a range of 150-300 deg.C at the time of stationary operation as soon as possible. After regenerated catalysts adsorb NH3 to saturated conditions and a rate of denitration is recovered, the mol ratio of NH3 to NOx is returned to 0.8-1.2 of the time of stationary operation. |
