A kind of exhaust gas aftertreatment system device and control method thereof

Abstract

The invention relates to an exhaust gas post-treatment system device and its control method. The system device includes an internal combustion engine, a first catalytic device, a second catalytic device and a third catalytic device connected in sequence; the first catalytic device and the second catalytic device A first pipeline and a second pipeline connected in parallel are arranged between the devices; a first valve is arranged in the first pipeline; a heater and a second valve are sequentially arranged in the second pipeline; Between the first catalytic device and the second catalytic device, a first NO x sensor, the second temperature sensor and the first urea nozzle; the inlet and outlet of the second catalytic device are provided with differential pressure sensors; the second catalytic device and the third catalytic device are sequentially provided with the first Three temperature sensors and a second urea nozzle. The exhaust gas control system device provided by the present invention can prevent the crystallization of the urea nozzle under cold start conditions, and reduce the NO in the exhaust gas x Transforms, reducing SCRF's active regeneration time.

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...

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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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