Reducing agent aqueous solution mixing device and exhaust gas after-treatment device

Abstract

The present invention suppresses adhesion of a urea aqueous solution to an interior wall of an exhaust pipe and reduces flow resistance inside the exhaust pipe, in a urea aqueous solution mixing device. This urea aqueous solution mixing device is provided with an exhaust pipe (4B), an injector (5), a mixing pipe (6), an interior pipe (7), and a flow unit (20). The exhaust pipe (4B) has an elbow part (10) with a curved section, and a straight part (11). The injector (5) injects the urea aqueous solution, and is provided in the elbow part (10). The mixing pipe (6) is positioned so as to cover the area around the urea aqueous solution injected by the injector (5), and has an exit part formed between the interior walls of the exhaust pipe (4B) with an interval interposed therebetween, and a plurality of openings (6a) formed in the outer-peripheral surface thereof. The interior pipe (7) allows exhaust gas to flow through the interior and outer-peripheral sections thereof, and is positioned in the straight part (11) of the exhaust pipe (4B). The flow unit (20) guides exhaust gas into the interior pipe (7), and is formed between the exit part of the mixing pipe (6) and the interior walls of the exhaust pipe (4B).

Description

technical field [0001] The present invention relates to a reductant aqueous solution mixing device, in particular to a device which is arranged in parallel with the filter between a filter for trapping particulate matter in exhaust gas and a reduction catalyst for reducing and purifying nitrogen oxides in exhaust gas. A reducing agent aqueous solution mixing device for adding a reducing agent aqueous solution to exhaust gas. In addition, the present invention also relates to an exhaust gas post-treatment device comprising the above-mentioned reducing agent aqueous solution mixing device. Background technique [0002] Engine exhaust contains nitrogen oxides (NOx). In order to suppress the release of the nitrogen oxides into the atmosphere, an exhaust after-treatment device is installed in the middle of the exhaust path. The exhaust gas post-processing device includes: a filter, which traps particulate matter in the exhaust gas; a urea aqueous solution mixing device, which i...

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Problems solved by technology

Therefore, the ammonia supplied to the reduction catalyst may be insufficient

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