SCRF system capable of actively controlling catalytic environment

Abstract

The invention discloses an SCRF system capable of actively controlling a catalytic environment. The SCRF system comprises a DOC, a urea spraying device, blades, a controller and an SCRF; the DOC is used for oxidizing NO into NO2, and furthermore the efficiency of converting NOx by the SCRF can be improved, and the regeneration of the SCRF can be facilitated; the urea spraying device is used for spraying urea into an exhaust pipe; the blades are arranged at the front end of the SCRF of the exhaust pipe of a diesel engine and are used for heating the urea sprayed by the urea spraying device so that urea crystallization can be avoided, and NH3 and exhaust gas can be fully mixed; the controller determines the heating temperature and the rotating speed of the blades according to the exhaust gas temperature in the exhaust pipe of the diesel engine as well as the gas temperature and the differential pressure in the SCRF system and actively controls the catalytic environment of the SCRF system; and the SCRF (namely an SCR catalysts coated DPF) carries out treatment on the NOx and PM in the exhaust gas of the diesel engine. The SCRF system has the beneficial effects that the temperature and the rotating speed of the blades can be controlled, heating and forced stirring are carried out on the mixed gas so that the uniformity of a mixture can be improved, and therefore the catalytic environment can be controlled, the generation of the catalytic reaction can be facilitated, and the generation of urea crystal substances at low temperature can be reduced.

Description

technical field [0001] The patent of the present invention relates to the field of aftertreatment of diesel engines, in particular to a SCRF system for actively controlling the catalytic environment. SCRF (SCR catalysts coated DPF) system is a filter loaded with SCR catalyst. Background technique [0002] The HC and CO emissions of a diesel engine are only a few tenths of those of a gasoline engine, but the NOx emissions are much higher than those of a gasoline engine, and the emission of PM (Particulate Matter) is 30 to 50 times that of a gasoline engine. For NOx and PM. Since NOx and PM emissions show a trend of ebb and flow, it is difficult to reduce both of them at the same time only by in-machine purification technology, and it must be supplemented by exhaust after-treatment technology. The selective catalytic reduction (Selective Catalytic Reduction, SCR) catalyst has a NOx conversion efficiency of up to 95%, good fuel economy and simple control, and is considered th...

AI Technical Summary

Problems solved by technology

However, there are two main problems in this method: one is that the volume is large, which is not conducive to installation and layout

The second is that the SCR is located at the rear end of the DPF. This structure makes the SCR slow to light up at low temperature, and the NOx conversion efficiency is low at cold start.

However, the cancellation of the SCR carrier shortens the mixing length, which is unfavorable for the NH in the SCR catalyst 3 The uniform distribution of NOx will lead to a decrease in the overall NOx catalytic performance

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