Urea crystallization detecting and testing method of SCR tail gas treatment system of engine

Abstract

The invention discloses a urea crystallization detecting and testing method of an SCR tail gas treatment system of an engine. The method includes the steps of firstly, acquiring the weight M1 of an exhaust treatment device (5) before a test; secondly, in a testing cycle, allowing the engine to work and be tested under preset testing conditions, namely controlling the jet flow of a urea nozzle (4) to be a preset value or in a preset range A, controlling the exhaust flow of an exhaust pipe (2) of the engine to be a preset value or in a preset range B, and controlling the temperature in the exhaust treatment device to be a preset value or in a preset range C; thirdly, acquiring the weight M2 of the exhaust treatment device after the test, subtracting M1 from M2 to obtain the increased weight D of the exhaust treatment device in the testing cycle; fourthly, determining the urea crystal weight M in the exhaust treatment device under the preset testing conditions according to increased weight D of the exhaust treatment device. By the detecting and testing method, urea crystal amount can be tested and detected to serve as reference for judging adaptability of the SCR tail gas treatment system, and corresponding adjustment can be performed.

Description

technical field [0001] The invention relates to an SCR exhaust gas treatment system of an engine, in particular to a urea crystallization testing method of the SCR exhaust gas treatment system of an engine. Background technique [0002] Such as figure 1 As shown, when the SCR exhaust gas treatment system of the engine is applied to the whole vehicle, the exhaust gas of the engine passes through the engine exhaust port 1 and the exhaust pipe 2 and passes through the front pipe section of the exhaust treatment device equipped with the urea nozzle 4 and the atomizer 7 It is discharged into the exhaust gas treatment device 5 and undergoes a catalytic reduction reaction. Wherein, on the front pipe section of the exhaust gas treatment device 5, the urea solution nozzle 4 sprays out the urea solution injection amount according to the engine electronic control unit, and the sprayed urea solution sprays to the grid-shaped space provided in front of the urea solution nozzle 4. On th...

AI Technical Summary

Problems solved by technology

[0003] However, due to the unique chemical properties of the urea solution itself, different products are produced at different operating temperatures, resulting in different products on the front pipe section of the exhaust treatment device 5 due to the different operating conditions of the vehicle engine. form fluid or crystals

If there is a large amount of such fluid or crystals, it will affect the atomization of urea solution and the passage of exhaust gas, which will cause the back pressure of the SCR exhaust gas treatment system to increase, increase the engine power loss, and to a large extent Affect the atomization quality of urea solution, directly lead to incomplete tail gas reaction, resulting in excessive emission, thus failing to meet emission requirements

In the prior art, there is no perfect method for checking whether the urea crystallization is qualified in the process of system development. Therefore, it is impossible to verify in advance whether the engine SCR system matched with the vehicle meets the requirements during the development process, thereby increasing the market. Risk of crystallization problems leading to problems with aftertreatment systems not working properly

Images