Urea injection control method based on real-time ammonia storage amount management for catalytic reduction of diesel

Abstract

The invention discloses a urea injection control method based on real-time ammonia storage amount management for catalytic reduction of diesel. The method comprises the following steps: an ammonia storage amount calculation model is established according to ammonia mass conservation of an SCR system, and ammonia storage amount of SCR at the current moment in actual working condition is calculated; NOx emission map, an exhaust mass flow map and an ammonia-nitrogen ratio map of an engine are calibrated on the basis of steady-state experiments, and basic urea injection amount is calculated; a target ammonia storage amount area, an ammonia adsorption time constant and an ammonia release time constant are experimentally calibrated, and modified urea injection amount is calculated; urea injection is controlled in the actual working condition on the basis of the sum of the basic urea injection amount and the modified urea injection amount, and slow urea injection and injection stopping are used for assistance under the working condition of sudden increase of exhaust temperature, so that the ammonia storage amount of the SCR at the current moment approaches the target ammonia storage amount area. NOx conversion efficiency in all working conditions of the SCR in aftertreatment of the diesel can be increased, and urea consumption and ammonia leakage are reduced.

Description

technical field [0001] The invention relates to a diesel engine tail gas post-treatment technology, and more specifically relates to a diesel engine catalytic reduction urea injection control method based on real-time ammonia storage management. Background technique [0002] Oxygen-enriched combustion of diesel engines can easily produce higher NO x Emissions, is NO from diesel locomotives x main source of emissions. Selective catalytic reduction technology utilizes the ammonia produced by the hydrolysis of urea to reduce the NO in the tail gas x reduced to N 2 , can reduce more than 90% of NO in diesel engines x , is currently considered to be the solution to diesel NO x Emissions most efficient technology. Compared with EGR technology, the use of SCR post-treatment technology is beneficial to the improvement of fuel economy, and the configuration of the fuel system does not need to be too high, and SCR is less sensitive to sulfur in fuel, and low fuel quality require...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art, aiming at the problem of low NOx conversion efficiency at low temperature of diesel engine aftertreatment SCR system and ammonia leakage under transient working conditions, to provide a diesel engine catalytic reduction based on real-time ammonia storage management The urea injection control method can improve the NO of diesel engine aftertreatment SCR under all working conditions x High conversion efficiency, saving urea consumption and reducing ammonia leakage

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