| 摘要 |
PURPOSE:To permit a denitrification device to be operated economically over an extended period of time while maintaining a satisfactory denitrification function by a method, when the activity of the denitrification catalyst on the upstream side is lowered, the denitrification catalyst on the uppermost side is used as a poisoning component collecting catalyst while operating a reducing agent pouring means on the rear side. CONSTITUTION:A waste heat recovery boiler 1 for recovering the waste heat from combustion exhaust gas is provided with denitrification catalysts 6 (6a-6b), pouring means 5a and 5b for introducing a denitrification reducing agent into the denitrification catalyst 6 and CO oxidizing catalyst 11 located on the front side of the denitrification catalyst 6. A plurality of denitrification catalysts 6 and pouring means 5a and 5b are provided in the direction of the exhaust gas stream and, when the activity of the denitrification catalyst 6a on the upstream side is lowered, the pouring means 5b on the downstream side is actuated to make the denitrification catalyst 6a on the uppermost side a poisoning component collecting catalyst. As a result, the effect of scattering the poisoning components of the CO oxidizing catalyst provided on the front side of the denitrification catalyst is controlled to the least possible extent and a satisfactory denitrification function can be obtained. |
