| 摘要 |
<p>A selective catalytic reduction catalyst (19) capable of reducing the NO x in exhaust gas to N 2 is arranged in an exhaust pipe (16) of an engine (11). Fluid feed means (21) has a fluid injecting nozzle (23) facing the exhaust pipe on the exhaust gas upstream side from the selective catalytic reduction catalyst. The fluid feed means is configured such that a urea fluid (22) that functions as a reducing agent is fed with the selective catalytic reduction catalyst from the fluid injecting nozzle to the exhaust pipe. Ozone feed means (41) comprises an ozone injecting nozzle (43) that faces the exhaust pipe on the exhaust gas upstream side from the selective catalytic reduction catalyst, and on the exhaust gas upstream side or the exhaust gas downstream side from the fluid injecting nozzle. The ozone feed means is configured such that ozone (42), which is capable of oxidizing the NO contained in the exhaust gas to NO 2 , is fed from the ozone injecting nozzle to the exhaust pipe. The NO x are reduced, even when the exhaust gas temperature is low, and as a result, the NO x can be efficiently reduced within a broad exhaust gas temperature range from low temperature to high temperature.</p> |
