Hybrid unit of SCR (selective catalytic reduction) system for vehicle urea

Abstract

The invention discloses a hybrid unit of an SCR (selective catalytic reduction) system for vehicle urea, comprising a pipe body, a hybrid unit rib device and a nozzle, wherein the nozzle is aslant arranged on the wall surface of the pipe body; the hybrid unit rib device tightly abuts against the nozzle and is installed on the front end of the nozzle; the hybrid unit rib device comprises four ribs, the middle of the first rib and the second rib forms a fluid path similar to an atomizing pattern; the first rib and the second rib have certain gradient and twists towards the central area; the third rib has a baffle-shaped structure and is arranged near the pipe wall, the installation direction is vertical to the atomizing axis, and the third rib twists towards the wall surface; and the fourthrib is arranged along the atomizing axis direction and is composed of a group of blades alternately twisted left and right. The invention can bring the effect that a urea aqueous solution injected bythe nozzle and tail gas are fully mixed before entering an SCR catalytic converter, thus reducing urea crystallization formed on the wall surface; and meanwhile, the hybrid unit has compact structureand is easy to process and install, and the effect of the hybrid unit is verified.

Description

technical field [0001] The patent of the present invention relates to the field of diesel engine exhaust aftertreatment system, and more specifically relates to a mixing device for a vehicle urea SCR system. Background technique [0002] Selective Catalytic Reduction (SCR) is currently recognized as one of the most effective post-treatment technologies for reducing NOx emissions from diesel engines, and is also considered to be one of the post-treatment technologies that is most in line with China's national conditions and can meet the National IV emission requirements. Urea SCR sprays a certain amount of urea aqueous solution into the exhaust pipe, and the urea aqueous solution undergoes evaporation, pyrolysis and hydrolysis to obtain the reducing agent NH 3 , NH 3 Selectively reduce NOx to N under the action of catalyst 2 , so as to reduce the content of NOx in the exhaust gas. Urea SCR after-treatment technology has been used in Europe for several years, and it is the ...

AI Technical Summary

Problems solved by technology

The air-assisted SCR system generally has a nozzle installed in the center of the exhaust pipe, and the urea aqueous solution is sprayed vertically toward the wall of the exhaust pipe with the assistance of compressed air. The atomization is relatively good under the action of air assistance, and it is not easy to form crystals, but one more compressed air , the system structure is complex; the non-air-assisted SCR system generally installs a solenoid valve nozzle on the pipe wall, and sprays from one end of the exhaust pipe wall to the other end of the exhaust pipe at a certain angle. The overall structure of this system is simple, but the atomization and mixing effects Poor, easy to form urea crystals

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