Exhaust Treatment System Additive Control for Soot Oxidation
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Solution Overview
Problem
Existing exhaust treatment systems face challenges in achieving optimized fuel consumption and efficient exhaust treatment due to insufficient soot oxidation in catalytic filters, primarily because soot oxidation reactions are slower than nitrogen oxide reduction reactions, leading to inefficient use of catalysts and increased costs.
Innovation Solution
A method and system that control the supply of additives in an exhaust treatment system to prevent soot accumulation in catalytic filters, utilizing a first oxidation catalyst and a double reduction strategy with additives to ensure sufficient NO2-based soot oxidation, allowing surplus NO2 to oxidize soot stored in the filter, while also reducing nitrogen oxides in both the catalytic filter and a reduction catalyst device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the supply of additive is increased to improve nitrogen oxide reduction, then nitrogen oxide conversion improves, but soot oxidation becomes insufficient and soot accumulates in the filter
Solution Approach 1:
The patent implements dynamic control of additive supply based on real-time monitoring of soot load and operating conditions. The control system adjusts the dosage of reductant dynamically to match varying engine loads and exhaust conditions, ensuring optimal balance between NOx reduction and soot oxidation at all times. This resolves the contradiction by making the system adaptive rather than static.
Solution Approach 2:
The patent changes key parameters including the ratio of NO to NO2 in the exhaust stream, the dosage rate of additive, and the temperature conditions in the catalytic filter. By controlling the NO/NO2 ratio and adjusting additive supply parameters dynamically, the system optimizes both nitrogen oxide conversion and soot oxidation simultaneously, resolving the trade-off between these two functions.
2Productivity
If catalyst volume is increased to improve exhaust treatment performance, then conversion efficiency improves, but manufacturing cost and back pressure increase
Solution Approach 1:
The patent optimizes the utilization efficiency of existing catalyst volume by changing operational parameters such as the NO/NO2 ratio, additive dosage rate, and temperature management. This maximizes the effectiveness of the available catalyst volume without requiring physical expansion, thereby maintaining high conversion efficiency while avoiding increased manufacturing cost and back pressure.
Solution Approach 2:
The system dynamically adjusts operating conditions to fully utilize the catalytic capacity of the existing filter volume. By varying additive dosage and exhaust composition in real-time, the system ensures optimal catalyst performance across all operating conditions, achieving high treatment performance without increasing catalyst volume.
3Productivity
If additive dosage is optimized for nitrogen oxide reduction, then NOx conversion improves, but soot accumulation occurs due to insufficient soot oxidation
Solution Approach 1:
The patent controls the NO/NO2 ratio in the exhaust stream as a key parameter, ensuring sufficient NO2 is available for soot oxidation while maintaining effective NOx reduction. By adjusting this ratio and the additive dosage rate dynamically, the system prevents soot accumulation while achieving high nitrogen oxide conversion efficiency.
Solution Approach 2:
The system incorporates feedback control by monitoring soot load in the filter and adjusting additive supply accordingly. This closed-loop control ensures that soot oxidation is maintained at sufficient levels while continuing to achieve effective nitrogen oxide reduction, preventing the trade-off from becoming a problem.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances soot oxidation in catalytic filters, improves nitrogen oxide reduction efficiency, and reduces the risk of additive cooling and deposit formation, leading to better fuel efficiency and compliance with emission standards.
Implementation Method 1
a first oxidation of compounds, comprising one or more of nitrogen, carbon and hydrogen, in the exhaust stream is carried out by a first oxidation catalyst
Implementation Method 2
the active control of the first supply of the first additive is carried out in such a manner that a sufficient NO2-based soot oxidation may take place in the catalytic filter
Implementation Method 3
a second reduction of nitrogen oxides NOx is carried out with the use of at least one of the first and the second additive in a reduction catalyst device
Implementation Method 4
The additive added to the catalyst is adsorbed (stored) in the catalyst, in the form of ammoniac NH3, so that a redox-reaction may occur between nitrogen oxides NOx in the exhausts and ammonia NH3
Implementation Method 5
a redox-reaction may occur between nitrogen oxides NOx in the exhausts and ammonia NH3 available via the additive
Data Source
AI summary
Methods and systems are provided for treatment of an exhaust stream, comprising nitrogen oxides. The method comprises a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust stream; and a control of a first supply of a first additive to the exhaust stream to prevent an accumulation of soot exceeding a soot threshold value in a catalytic filter. This soot threshold value depends at least on operating conditions for the combustion engine, which impact a level of a flow for the exhaust stream. A first reduction of nitrogen oxides is performed using reduction characteristics of a catalytic coating in the catalytic filter and the supplied first additive. Soot particles are caught and oxidized. A control of a second supply of a second additive is performed, following which a second reduction of nitrogen oxides is performed using the first and/or the second additive in a reduction catalyst device.