REDUCING AGENT ADDITION DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress generation of hydrogen sulfide and inhibit deterioration of fuel economy.SOLUTION: A reducing agent addition device is installed in a combustion system in which a NOx elimination system 15 for eliminating NOx included in exhaust gas from an internal combustion engine 10 on a reduction catalyst is arranged in an exhaust passage 10ex, and is used for adding the reducing agent to the upstream side of the reduction catalyst of the exhaust passage 10ex. The reducing agent addition device includes: reforming means provided by a discharge reactor 20 and a heater 30; purification control means 81a; and recovery control means 81b. The reforming means reforms the reducing agent by partially oxidizing it. At purification request for elimination of NOx on the reduction catalyst, the purification control means 81a adds the reducing agent that has been reformed by the reforming means to the exhaust passage 10ex. At recovery request for recovery of the reduction catalyst poisoned with sulfur, the recovery control means 81b adds the reducing agent that has been reformed by the reforming means to the exhaust passage 10ex on the condition that the internal combustion engine 10 is in the lean combustion state.SELECTED DRAWING: Figure 1