Emission control apparatus

摘要

An emission control unit (200) includes a trunk passage (30a), a loop passage (30b) connected to the trunk passage, and a path change portion (250) that is provided in a connecting portion between the trunk passage and the loop passage and that includes a switching valve (251) for changing the path of exhaust gas. The loop passage is provided with a first emission control portion (210) for purifying NOx and carbon-containing particles present in exhaust gas. A second emission control portion (220) for purifying NOx present in exhaust gas is provided in a downstream-side partial trunk passage (30a2). The emission control unit is equipped with a reducer injection nozzle (261) for injecting into a first partial loop passage (30b1) a reducing agent for recovering the emission control functions of the two emission control portions.