System for after-treatment of exhaust gas and method for controlling of the same

Abstract

The present invention provides a system for post-treatment of an exhaust gas which is mounted on an exhaust pipe of an internal combustion engine and sequentially has, on the upstream side, a diesel particulate matter filter (DPF) and a selective catalyst reduction (SCR) technology. The system further includes: a burner positioned upstream of the DPF to heat an exhaust gas from the internal combustion engine; a hydrocarbon injector positioned upstream of the DPF to spray hydrocarbon to the exhaust gas; and a control unit controlling the burner and the hydrocarbon injector according to a firstmode for removing nitrogen oxides or a second mode for removing particulates. When the temperature of the exhaust gas does not reach the operating temperature of the SCR, the control unit operates theburner according to the first mode to heat the exhaust gas to the operating temperature of the SCR, or operates the burner while spraying hydrocarbon by using the hydrocarbon injector according to the second mode to heat the exhaust gas to the particle removal temperature of the DPF. Thus, the system can use a small-capacity burner and hydrocarbon injection, thereby extending an operating area thereof to a low-temperature area.

Description

[0001] This application claims priority from Korean Patent Application No. 10-2018-0128750 filed on October 26, 2018, the entire contents of which are incorporated herein by reference. technical field [0002] The present invention relates to an exhaust aftertreatment system and a control method thereof, and more particularly, to an exhaust aftertreatment system for purifying exhaust gas exhausted from an internal combustion engine mounted on a vehicle and a control method thereof. Background technique [0003] In general, there is an increasing demand for diesel engines that can realize high-efficiency and high-output operation in vehicles, ships, generators, and the like. This is due to the low price of diesel, which offers an advantage in terms of fuel economy or efficiency. [0004] When such a diesel engine is driven, nitrogen oxides (NOx) and particulate matter (PM, Particulate Matter), which cause air pollution, will be discharged together with the exhaust gas. Theref...

AI Technical Summary

Problems solved by technology

Therefore, in the high-speed and high-load operation environment, the catalyst activity is extremely large, so the exhaust gas purification function will be performed normally, but in the case of low-speed high-load vehicles or frequent start and stop (stop&go) vehicles, due to the temperature of the exhaust gas Lower and it is difficult to make the aftertreatment system work properly, so the emission of harmful exhaust will increase

[0007] Therefore, various methods for raising the temperature of the exhaust gas have been developed and used. However, in order to use the burner to raise the temperature of the exhaust gas, the amount of fuel injection is large and the flame will also become large, so the size and structure of the burner will become complicated. , so that the operation and installation are also difficult, so the failure of the structural elements and the abnormal operation occur frequently

[0008] In addition, in the case of a large vehicle with a large exhaust flow rate, the control of the initial slip (slip) becomes difficult due to the large amount of fuel injection, and it is difficult to achieve stable restart efficiency

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