SCR urea mixer for diesel internal combustion engine aftertreatment system

Abstract

The invention discloses an SCR urea mixer for a diesel internal combustion engine aftertreatment system. The SCR urea mixer comprises a cylindrical shell and a urea nozzle, wherein a vortex mixing cavity is formed in the front end in the shell; an exhaust mixing cavity is formed in the rear end in the shell; the urea nozzle is arranged on the wall of the vortex mixing cavity; the vortex mixing cavity is arranged on the inner circumference of the cylindrical shell and is the gas flow mixing cavity with a spiral structure with convergent flow characteristics; air inlets are formed in the front end face and along the axial direction of the shell and the peripheral edge of the spiral structure; exhaust ports are formed in a connecting part connecting the vortex mixing cavity and the exhaust mixing cavity and along the peripheral direction of the central edge of the spiral structure; a circular hole is formed in the center of the rear end face of the exhaust mixing cavity; and a plurality of flow equalizing plate exhaust holes are uniformly formed in the radial periphery of the circular hole. According to the SCR urea mixer, urea liquid drops are transferred, crushed and atomized by utilizing exhaust hot tail gas flow, and is fully and uniformly mixed with the hot tail gas, so that the problems of urea deposition and crystallization are solved, and the gas flow uniformity and the ammonia gas uniformity of the mixer well meet the requirements of emission regulations.

Description

technical field [0001] The invention belongs to the technical field of environmental treatment, in particular to the technical field of tail gas purification equipment design and manufacture, and relates to a diesel internal combustion engine tail gas post-processing technology, in particular to an SCR urea mixer for a diesel internal combustion engine post-processing system. Background technique [0002] At present, the tail gas emission reduction technology used in the exhaust aftertreatment system of diesel internal combustion engines has the following two technical approaches and routes: one is to realize the purification of particulates in the cylinder of the engine and the catalytic reduction of the engine aftertreatment system by optimizing the combustion system in the cylinder of the diesel engine Nitrogen oxides, that is, SCR selective catalytic reduction technology; the second is the use of EGR (engine exhaust gas recirculation) to purify nitrogen oxides in the cyli...

AI Technical Summary

Problems solved by technology

The SCR mixer in the technical scheme of the existing diesel internal combustion engine post-treatment system in China widely adopts the inner layer and outer layer perforated pipe structure. The first atomization, and then under the action of the outer perforation of the outer pipe, the second atomization is carried out, and then enters the air intake chamber; during the working process of the mixer, there is uneven mixing of the urea aqueous solution and the hot exhaust gas discharged from the diesel internal combustion engine. There are a large number of urea crystals inside and on the end surface of the SCR catalyst, causing problems such as blockage of the SCR catalyst

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