After-treatment intake mixing device

Abstract

The invention discloses an after-treatment intake mixing device. The after-treatment intake mixing device comprises a bucket body, a urea injection device, an intake swirl sheet and an intake mixing pipe, wherein the intake sheet blade comprises a barrel body; a first through hole is formed in the barrel wall of the barrel body; an inclined sheet is arranged on the first through hole; a urea nozzle of the urea injection device is aligned with the inner ring of the intake swirl sheet; the intake swirl sheet is butted with the intake mixing pipe; and a plurality of second through holes are formed in the intake mixing pipe. Tail gas enters from an intake port of the bucket body, and swirl mixing is carried out on the tail gas and an aqueous urea solution injected through the urea nozzle in the intake swirl sheet; the swirl sheet is beneficial to adequate mixing for the tail gas and mist urea liquid drops; and the mixed gas flow enters the intake mixing pipe, directly flows out through thesecond through holes in the intake mixing pipe, and contacts with a carrier with an SCR catalyst to carry out a catalytic reduction reaction. The intake swirl sheet enables the gas flow to form effective vortex, so that the collision probability of the tail gas and the aqueous urea solution is increased, and then the conversion efficiency of nitrogen oxides is increased.

Description

technical field [0001] The invention relates to the technical field of engine exhaust gas treatment, in particular to an aftertreatment intake air mixing device. Background technique [0002] The SCR catalytic reduction technology used in engine exhaust treatment in the prior art is an important technical route to reduce nitrogen oxide emissions from diesel engines and meet the national IV and above emission regulations. The currently applied design scheme often has phenomena such as emission failure and urea crystallization, which lead to an increase in the failure rate of the engine, a decline in customer satisfaction, and even fail to meet the requirements of national emission regulations. [0003] The method adopted in the prior art for engine exhaust gas treatment is that the exhaust gas flow directly enters the intake mixing pipe, and is mixed with the urea aqueous solution sprayed by the urea nozzle of the urea injection device in the intake mixing pipe, and the mixed...

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Problems solved by technology

[0005] (1) The intake mixing tube itself is a single-layer tube with a single opening form, which is not conducive to the generation of turbulent flow and the mixing between exhaust gas and urea droplets. The conversion efficiency of urea into NH3 is not high, and the undecomposed urea droplets prone to crystallization

[0006] (2) The mixing path of exhaust gas and urea droplets in the intake single-layer pipe is short, and the urea droplets that cannot be fully broken are easy to form urea crystals in the intake mixing chamber

[0007] (3) The airflow dead zone is easy to form at the end connection of the single-layer intake pipe, and the risk of crystallization is high

[0008] (4) Poor thermal insulation effect and low heat utilization rate

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