Static mixer for diesel engine urea selective catalytic reduction device

Abstract

The invention discloses a static mixer for a diesel engine urea selective catalytic reduction device. The static mixer comprises a pipe body, a mixer tab and a nozzle. The static mixer for the diesel engine urea selective catalytic reduction device is characterized in that the nozzle is arranged at the central axis of the pipe body; the mixer tab props against the nozzle and is installed at the front end of the nozzle; and the mixer tab is of an integral bowl structure, is provided with a fan-shaped cellular fluid channel along an atomizing axis, and the middle part of the mixer tab is bulged along the reverse direction of the air stream. According to the invention, based on the properties of atomization, the mixer carries out rationalization on the air stream motion in an air exhaust pipe, thus a strong turbulent flow forms at the part, at which the atomization is the worst, on the outlet of the nozzle, but the atomization effect gets better gradually along the atomizing axis direction, and the air stream motion weakens as well. The static mixer for the diesel engine urea selective catalytic reduction device provided by the invention not only ensures that a urea water solution injected by the nozzle and the air exhaust to be mixed fully before entering an SCR (selective catalytic reduction) catalytic converter, the crystallization of the urea at a wall surface is reduced, and at the same time, the requirements of mixing and pressure dropping are satisfied through changing the main property designed parameters according to the characteristics of different engines.

Description

technical field [0001] The patent of the present invention relates to the field of automobile exhaust aftertreatment systems, and more specifically relates to a static mixer used in a urea selective catalytic reduction device for diesel engines. Background technique [0002] Selective Catalytic Reduction (SCR) post-treatment technology is one of the main technical means to control NOx in diesel engines. The main principle of SCR is to take a certain amount of reducing agent into the exhaust pipe. Under the action of the catalyst, the reducing agent will undergo redox reaction with NOx in the exhaust gas to generate harmless N 2 discharge to achieve the purpose of reducing NOx emissions. Urea (Urea) as reducing ammonia (NH 3 ) carrier, because of its non-toxic, odorless, stable and other advantages, it has become the preferred reducing agent for the SCR technology of automotive diesel engines. Urea SCR after-treatment technology has been used in Europe for several years, a...

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Problems solved by technology

However, installing a mixer at the rear end of the nozzle may cause crystallization of the spray at the mixer. At the same time, installing a mixer will also cause an increase in exhaust pressure and af

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