Urea injection system and control method thereof, controller and storage medium

Abstract

The invention discloses a control method of a urea injection system. The control method comprises the following steps of acquiring the exhaust temperature in an exhaust pipe and the temperature of a urea solution in a urea supply pipeline; when the exhaust temperature is lower than a preset exhaust temperature, calculating the saturation temperature of the urea solution corresponding to the exhaust pressure based on the exhaust pressure in the exhaust pipe; and when the temperature of the urea solution is lower than the saturation temperature, determining that the temperature control mode of the urea solution in the urea supply pipeline is that the temperature of the urea solution is increased to be higher than the saturation temperature. According to the scheme, the temperature of the urea solution is increased to be higher than the saturation temperature of the urea solution corresponding to the exhaust pressure, and in the urea injection process, the urea solution can generate flash boiling, so that the urea atomization effect is improved, and the urea crystallization risk when the exhaust temperature is low is reduced. The invention further discloses the urea injection system, a controller and a storage medium.

Description

Technical field[0001]The present invention relates to the field of post-treatment techniques, and more particularly to an urea injection system and a control method thereof.Background technique[0002]Selective Catalytic Refractive Technology (SCR, SELECT CATALYST Reduction) is a post-treatment process for NOx in diesel engine exhaust emissions, under the action of catalyst, NOx and NH in exhaust3Restore reactions occur, produce nitrogen and water. The catalyst is applied to the surface of the carrier aperture, which mainly acts as a reduction of the activation energy of the NOx reduction reaction, and reduces the temperature required for the NOx reduction reaction. Usually uses a mass fraction of 32.5% urea aqueous solution to NH3NH3Source to avoid harm to the human body. Urea aqueous solution is injected into the exhaust pipe in the exhaust pipe by urea nozzles.3. Urea is not toxic, small pollution caused by the environment, nor does it harm human health, easy to store, convenient t...

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Problems solved by technology

In addition, the spray is also related to the formation of urea deposits in the SCR system. If the urea spray is not completely decomposed, it will gradually accumulate in the SCR system, and a side reaction will occur to form urea deposits (that is, urea crystals). The urea deposits will greatly affect Working performance of SCR system

When the engine is at low speed and low load, the exhaust temperature is low, the urea atomization effect is poor, and the risk of urea crystallization is high

[0004] In the existing post-treatment control strategy, the urea supply pipeline will start to generate heat only under cold start conditions, and the urea supply pipeline does not have a strategy for temperature control of urea under normal engine operating conditions

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