Post-processing system apparatus and control method

Abstract

A post-processing system apparatus and a control method according to the present invention comprise: an exhaust pipe having one end connected to an engine to introduce exhaust gas and the other end opened to discharged the exhaust gas; a DOC for primarily reducing the smoke of the exhaust gas introduced to the exhaust pipe; a DPF for secondarily reducing the smoke of the exhaust gas passed through the DOC; an SCR for reducing NOx (nitrogen oxide) of the exhaust gas passed through the DPF; an AOC for oxidizing the ammonia of the exhaust gas passed through the SCR and reducing NOx (nitrogen oxide) of the exhaust gas passed through the SCR; a first bypass pipe branched from the exhaust pipe between the engine and the DOC so as to bypass the whole or a portion of the exhaust gas to the front end of the SCR; and a first switch arranged at a point branched from the exhaust pipe to the first bypass pipe so as to control the amount of the exhaust gas being bypassed to the first bypass pipe.

Description

technical field [0001] The present invention relates to an aftertreatment system of an engine. More specifically, it relates to a UREA-SCR (urea addition selective catalytic reaction) system device that detours high-temperature exhaust gas to the front end of the SCR to reduce the discharge of nitrogen oxides (NOx) and Control Method. Background technique [0002] Generally speaking, the engine sucks in a mixture of fuel and oxygen, compresses it, and explodes it. The exhaust gas generated at this time is released into the atmosphere through the exhaust pipe. This exhaust gas contains a large amount of substances harmful to the human body such as carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC). [0003] In particular, compared with gasoline engines using gasoline and LPG engines using LPG, diesel engines using diesel (DISEL) burn in an oxygen-excessive atmosphere, so the amount of nitrogen oxides (NOx), which is a harmful substance, is generated ...

AI Technical Summary

Problems solved by technology

[0007] Therefore, at the initial stage of engine startup, if the temperature of the SCR device and the front end of the SCR is low, when UREA (urea) is injected, crystallization of UREA (urea) will accumulate in the tube (after UREA injection, the temperature will be about 100 to 150 degrees or more Thermal decomposition and simultaneous chemical change to NH 3 (Ammonia), at low temperature, still adheres to the tube in the state of UREA (urea) and presents a phenomenon of white accumulation), so that the system is destroyed, or due to partial blockage, the amount of UREA entering the SCR carrier is less than the amount of NOx generated, so There is a problem that the NOx reduction rate decreases

Images