A low temperature heating and mixing device for urea scr system

Abstract

The invention discloses a low-temperature heating and mixing device of a urea SCR (Selective Catalytic Reduction) system. The heating and mixing device is mounted between the urea water solution nozzle section pipeline of an exhaust pipeline of an internal combustion engine and the catalyst front section pipeline of an SCR catalyst, and comprises a mixer and a heating tile arranged outside the mixer; the inner diameter of the mixer is smaller than that of the urea water solution nozzle section pipeline; the heating tile is connected with a power supply. The low-temperature heating and mixing device modifies the low-temperature adaptability of the urea SCR system and improves the mixing uniformity of all components of exhausted gases entering the SCR catalyst through the mode of connecting the heating and mixing device onto the pipeline between the SCR catalyst and the urea water solution nozzle; urea sprayed in the exhaust pipe still can be fully decomposed under the condition of lower exhaust temperature, so that the catalysis process of the SCR catalyst is guaranteed to be normally implemented; the generation of most precipitates in the exhaust pipe caused by lower exhaust temperature is avoided.

Description

technical field [0001] The invention relates to the technical field of internal combustion engines, in particular to a low-temperature heating and mixing device for a urea SCR system. Background technique [0002] Selective catalytic reduction (SCR) technology using urea aqueous solution as a reducing agent has become one of the most effective technologies for reducing nitrogen oxides (NOx) in internal combustion engines, and has been widely used in motor vehicles, construction machinery, ships and other fields. When the SCR system is working, the urea aqueous solution is quantitatively sprayed into the exhaust pipe through the injection system, and decomposed under the high temperature of the exhaust gas to generate NH 3 , NOx is replaced by NH on the SCR catalyst surface 3 Revert to generate N 2 . [0003] Ideally, the aqueous urea solution would be completely decomposed before entering the catalyst. But in practical application, when the engine is working under low lo...

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Problems solved by technology

[0006] The technical problems to be solved by the present invention are: the temperature range of the exhaust gas of the internal combustion engine is large, the low temperature adaptability of the urea SCR system is poor, and a large amount of deposits are easily generated in the exhaust pipe; when the temperature is low, the urea cannot be fully decomposed, and the subsequent Catalytic reactions to reduce NOx are also hindered, resulting in increased NOx emissions in the exhaust

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