Dual-layer mixing pipe and exhaust treating device thereof

Abstract

The invention discloses a dual-layer mixing pipe. The dual-layer mixing pipe comprises an inner pipe, an outer pipe, a transition pipe and an end cap, wherein the inner pipe is through along the axial direction and comprises a first end and a second end which are oppositely arranged in the axial direction; the transition pipe is connected with the first end; at least one opening groove is formed in the second end; a containing cavity containing at least one part of the second end is formed in the end cap; the outer pipe comprises a first half pipe and a second half pipe which are matched with each other; the first half pipe and the second half pipe are staggered in the radial direction, so that a first outlet and a second outlet are formed in the circumferential direction; the opening directions of the first outlet and the second outlet are opposite, so that exhaust rotational flow is formed. According to the dual-layer mixing pipe, the travel of air flow in a limited space is increased, the evaporating distance of urea droplets is increased, the evaporation rate is improved, the mixing uniformity is improved, and the risk of urea crystallization is reduced. The invention also discloses an exhaust treating device with the dual-layer mixing pipe.

Description

technical field [0001] The invention relates to a double-layer mixing pipe and an exhaust treatment device thereof, which belong to the technical field of engine exhaust post-treatment. Background technique [0002] Studies have shown that the uniformity of ammonia distribution in the pipeline of exhaust aftertreatment systems (such as selective catalytic reduction systems, SCR systems) has an important impact on the overall performance and durability of the system. If the distribution of ammonia is not uniform, it will lead to excessive ammonia in local areas, which will easily cause ammonia leakage, and the conversion efficiency of nitrogen oxides (NOx) will be too low in other ammonia-lean areas. The uneven distribution of ammonia over a long period of time can lead to uneven catalyst aging, which affects the overall performance of the catalyst. In addition, the uneven distribution of urea droplets will cause the temperature of the local pipe wall or mixing structure to ...

AI Technical Summary

Problems solved by technology

If the distribution of ammonia is not uniform, it will lead to excessive ammonia in some areas, which will easily cause ammonia leakage, and the conversion efficiency of nitrogen oxides (NOx) will be too low in other ammonia-lean areas.

Uneven distribution of ammonia over a long period of time can lead to uneven catalyst aging, which affects the overall performance of the catalyst

In addition, the uneven distribution of urea droplets will cause the temperature of the local pipe wall or mixing structure to be too low, forming crystallization, which will block the exhaust pipe in serious cases and cause the engine power performance to decline

Images