Exhaust gas after-treatment system device and control method thereof

Abstract

The invention relates to an exhaust gas after-treatment system device and a control method thereof. The system device includes an internal combustion engine, a first catalytic device, a second catalytic device, and a third catalytic device which are connected in sequence; a first pipeline and a second pipeline which are connected in parallel are arranged between the first catalytic device and thesecond catalytic device; a first valve is arranged in the first pipeline; a heater and a second valve are sequentially arranged in the second pipeline; a first NOx sensor, a second temperature sensorand a first urea nozzle are sequentially arranged between the first catalytic device and the second catalytic device; differential pressure sensors are arranged at a feed port and a discharge port ofthe second catalytic device; and a third temperature sensor and a second urea nozzle are sequentially arranged between the second catalytic device and the second catalytic device. According to the exhaust gas after-treatment system device provided by the invention, the urea nozzle can be prevented from crystallizing under cold start working conditions, NOx in exhaust gases is converted, and the active regeneration time of an SCRF is reduced.

Description

technical field [0001] The invention relates to the field of exhaust gas treatment, in particular to an exhaust gas post-treatment system device and a control method thereof. Background technique [0002] At present, the aftertreatment of exhaust gas in automobile use is more and more important. For example, CN104781515A provides a method to suppress HC, CO and NO during SCRF regeneration. x Systems and methods for emissions. It installs a post-catalyst with oxidation function in the exhaust passage on the downstream side of SCRF, and the post-catalyst also has the function of promoting ammonia oxidation in the predetermined first temperature range to generate N 2 function. In addition, set a temperature zone that is lower than the SCRF regeneration temperature as the second temperature zone. When performing SCRF regeneration treatment, adjust the temperature of the SCRF to the second temperature zone for ammonia discharge within a certain period of time, and gradually red...

AI Technical Summary

Problems solved by technology

It has the following disadvantages: first, it is necessary to add an additional post-stage catalytic converter to deal with the leaked ammonia; second, it cannot guarantee the maximum efficiency of ammonia removal in the SCRF when the post-stage catalytic converter is at its maximum efficiency; third, thermal shock occurs , the resulting ammonia leakage cannot be removed by the rear catalytic converter

It has the following shortcomings: first, the main function of the blade is to increase the temperature of the urea nozzle, prevent urea crystallization, and have no obvious effect on SCRF regeneration; second, the blade increases the exhaust back pressure and affects the airspeed, increasing the calibration difficulty

It has the following deficiencies: first, the exhaust temperature and exhaust back pressure are related to the working conditions, which may cause repeated switching of the engine cycle working mode in a transient state, increasing the instability of the system; second, the engine uses two A cyclic working method increases the complexity of the system. Third, the power is insufficient during cold start

[0006] 1. When the exhaust temperature and exhaust mass flow rate are low, it is easy to cause urea crystallization in the urea nozzle, which affects the injection of urea and the catalytic efficiency of SCRF, resulting in NO x emissions exceeding the standard;

[0007] 2. SCRF active regeneration will cause a certain amount of ammonia leakage in the early stage, and a certain amount of NO in the later stage x emissions, and the longer the regeneration time, the greater the emissions;

[0008] 3. During transient thermal shock, the ammonia emission in SCRF will increase, and an additional ammonia post-processor is required for tail gas treatment, which increases the cost of the system

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