SCR system and box type catalytic silencer thereof

Abstract

The invention discloses a box type catalytic silencer of an SCR system. The silencer comprises a box, and an outer layer pipe and a carrier coated with a catalyst, wherein the outer layer pipe and the carrier are arranged in an inner cavity of the box. The outer layer pipe is used for introducing tail gas and a urea aqueous solution, and is provided with an exhaust port. The inner wall of the box is connected with a rear baffle used for fixing the carrier. The rear baffle is provided with a plurality of first through holes so that the mixture of the tail gas and the urea aqueous solution can be exhausted from the exhaust port and then flows to the carrier through the first through holes. Mixing uniformity of the mixture is improved, so that the conversion rate of nitrogen oxide is increased, and the risk of urea crystallization is reduced. The invention further discloses the SCR system comprising the box type catalytic silencer.

Description

technical field [0001] The invention relates to the technical field of engines, in particular to an SCR system and a box-type catalytic muffler thereof. Background technique [0002] SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) technology is a 3 Catalytic reduction reaction with NOx to eliminate nitrogen oxides (NOx) in diesel engine exhaust. After being processed by the SCR system, the exhaust gas of the diesel engine can meet the emission regulations of China IV and above. [0003] The SCR system is mainly divided into three parts according to the function: the control unit, the urea dosage unit and the catalytic muffler. Among them, the catalytic muffler mainly includes the SCR catalyst, the carrier and its packaging. When working, a quantitative urea aqueous solution is sprayed in the form of a mist, and a hydrolysis reaction occurs under the action of high-temperature exhaust gas to generate the reducing agent NH required for the subsequent catal...

AI Technical Summary

Problems solved by technology

[0006] In the above-mentioned box-type catalytic muffler, the hydrolyzed mixture of urea aqueous solution and exhaust gas directly enters the carrier 6' through the exhaust port of the straight intake pipe 2', which has a small disturbance to the air flow, and the mixing uniformity of the urea aqueous solution and exhaust gas is poor. , and the conversion rate of the hydrolysis reaction is low, resulting in a low conversion rate of the subsequent catalytic reduction reaction. At the same time, the risk of urea crystallization is high, and when the urea crystallization accumulates to a certain extent, it may also block the channel of urea flow, causing equipment Fault

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