| 摘要 |
PROBLEM TO BE SOLVED: To perform a more efficient conversion from urea water into ammonia than that of the prior art.SOLUTION: There is provided urea water mixing structure which includes: a selective reduction type catalyst 4 causing NOx contained in exhaust gas 1 to react with ammonia; an injector 8 (urea water adding means) placed upstream of the catalyst 4 and adding urea water into the exhaust gas 1; a mixing pipe 7B connecting between the injector 8 and the selective reduction type catalyst 4; and mixer structure 15 for feeding the exhaust gas 1 from its tangential direction against an input end part of the mixing pipe 7B to form a swirl flow of the exhaust gas 1 within the mixing pipe 7B, and in which the injector 8 adds the urea water to the swirl flow of exhaust gas and mixes them with each other. In the urea water mixing structure, a spiral rail 16 is installed in the inner circumferential surface of the mixing pipe 7B in such a way that the spiral rail 16 forms a helical railway concentric with a central axis of the mixing pipe 7B, and the helical railway of the spiral rail 16 corresponds to the swirl flow of the exhaust gas 1. |
