SCR (selective catalytic reduction) feed-forward control method and device

Abstract

The invention discloses an SCR (selective catalytic reduction) feed-forward control method and device. The SCR feed-forward control method comprises the following steps: acquiring SCR upstream temperature, the NOx emission of an engine, exhaust gas mass flow and urea spraying rate in real time; calculating an actual average ammonia storage concentration value according to the SCR upstream temperature, the NOx emission of the engine, the exhaust gas mass flow and the urea spraying rate; generating a regulation value for regulating the urea spraying rate according to a preset urea spraying regulation algorithm by taking a difference between a set average ammonia storage concentration value and the actual average ammonia storage concentration value as a parameter. According to the method and the device, required urea spraying rate can be calculated in real time according to a current working condition of the engine without waiting for the variation of residual NH3 at the rear end of an SCR catalytic converter; the lag of regulation of the urea spraying rate for the variation of the residual NH3 is avoided, so that the transient control effect is better, and the leakage of NH3 can be effectively avoided.

Description

technical field [0001] The invention relates to the field of tail gas treatment, in particular to an SCR feedforward control method and device. Background technique [0002] The main harmful emissions from diesel engines include nitrogen monoxide and nitrogen dioxide, which can be collectively referred to as NOx. [0003] The technology for controlling harmful gas emissions includes SCR (Selective Catalytic Reduction, selective catalytic reduction technology); the principle is to inject urea into the tail gas containing NOx to make the NOx in the tail gas react with ammonia (NH3) and reduce it to N2 (nitrogen) and water, so as to achieve the purpose of controlling exhaust emissions of harmful gases. [0004] In SCR technology, the control of urea injection volume is the key technology, and the injection volume of urea needs to be adjusted in real time according to the NOx emission; if the urea injection volume is too small, the NOx reaction cannot be effectively reduced to ...

AI Technical Summary

Problems solved by technology

[0006] The inventor found through research that in the technical solution in the prior art, the control amount of urea injection needs to be generated with the remaining NH3 data information fed back by the exhaust gas sensor as a parameter, that is, only when the control amount of the current urea injection amount and The remaining NH3 in the exhaust gas is no longer suitable for the subsequent adjustment of the control amount of the urea injection amount. In this way, due to the lag in the adjustment of the control amount of the urea injection amount, the transient control effect is poor and it is easy to cause NH3 leakage

Images