SCR Particulate Filter Regeneration via Dual-Zone Urea Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust gas aftertreatment systems for diesel engines face inefficiencies in nitrogen oxide reduction and particle filter regeneration due to competitive reactions between nitrogen dioxide and ammonia, leading to high reducing agent consumption and operational costs.
Innovation Solution
A method and device that regulate the introduction of ammonia-based reducing agents into the exhaust system based on the temperature of the SCR particle filter and catalytic converter, optimizing the reducing agent supply to ensure efficient continuous regeneration of the SCR particle filter and reduction of nitrogen oxides while minimizing agent consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aqueous urea solution is introduced into the exhaust stream upstream of the SCR particulate filter to ensure continuous regeneration, then nitrogen oxide reduction is improved, but reducing agent consumption increases due to competitive reactions
Solution Approach 1:
The exhaust stream is divided into two separate injection zones: a first reducing agent injection zone upstream of the SCR particulate filter and a second reducing agent injection zone downstream of the SCR particulate filter but upstream of the SCR catalyst element. This segmentation allows independent control of reducing agent delivery to different functional areas, preventing unnecessary consumption in the first zone while ensuring adequate supply for regeneration and NOx reduction in the second zone.
Solution Approach 2:
The control unit dynamically adjusts the amount of reducing agent introduced at each injection zone based on real-time temperature measurements of the SCR particulate filter and SCR catalyst element. This dynamic control ensures reducing agent is supplied only where and when needed, optimizing the balance between continuous regeneration and minimizing overall consumption.
2Object-affected harmful factors
If reducing agent is introduced into the exhaust stream to reduce nitrogen oxides, then emission control is improved, but operational costs increase due to high reducing agent consumption
Solution Approach 1:
By segmenting the reducing agent injection into two distinct zones with independent control, the system can optimize NOx reduction efficiency while minimizing overall reducing agent consumption, directly addressing the contradiction between emission control and operational costs.
Solution Approach 2:
The control unit uses temperature measurements from sensors monitoring the SCR particulate filter and SCR catalyst element as feedback to dynamically adjust reducing agent injection amounts. This feedback mechanism ensures reducing agent is applied only when and where thermally conditions are favorable for effective NOx reduction, avoiding unnecessary consumption and reducing operational costs.
3Reliability
If temperature of the SCR particulate filter is increased to ensure continuous regeneration, then particle filter regeneration is improved, but energy consumption increases
Solution Approach 1:
The system changes the chemical parameters of the exhaust stream by introducing aqueous urea solution at specific zones, which alters the chemical environment to enable continuous regeneration at lower temperatures without requiring excessive energy input for thermal regeneration.
Solution Approach 2:
Aqueous urea solution acts as an intermediary substance that facilitates the regeneration process chemically, allowing the SCR particulate filter to regenerate continuously without requiring high temperature increases that would consume excessive energy.
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 the efficiency of exhaust gas aftertreatment by optimizing reducing agent use, reducing operational costs, and increasing vehicle range by ensuring effective nitrogen oxide reduction and continuous particle filter regeneration.
Implementation Method 1
nitrogen oxides contained in the exhaust gas of the internal combustion engine can be reduced by means of the SCR particulate filter with ammonia as a reducing agent
Implementation Method 2
an oxidation catalyst is typically installed upstream of the particulate filter in the exhaust stream, using the catalyst to convert nitrogen monoxide contained in the diesel engine's exhaust gas to nitrogen dioxide
Implementation Method 3
particles contained in the exhaust gas of the internal combustion engine, in particular carbon particles, can be filtered out of the exhaust gas and stored by means of the SCR particulate filter
Implementation Method 4
The resulting nitrogen dioxide reacts with the carbon particles stored in the particulate filter even at relatively low exhaust gas temperatures (around 250°C), thus regenerating the filter. This process typically follows the reaction equation: 2 NO2 + C → 2 NO2 + CO2
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for operating an exhaust aftertreatment system for an internal combustion engine, in particular for a diesel engine, wherein an exhaust stream (7) with at least one SCR particulate filter (15) is provided, wherein particles contained in an exhaust gas (9) of the internal combustion engine (5), in particular carbon particles, can be filtered out of the exhaust gas (9) and stored by means of the SCR particulate filter (15), wherein nitrogen oxides contained in the exhaust gas (9) of the internal combustion engine (5) can be reduced by means of the SCR particulate filter (15) using ammonia as a reducing agent, wherein a first reducing agent supply device (22) is provided, by means of which the reducing agent, in particular in the form of an aqueous urea solution, can be introduced into the exhaust stream (7) upstream of the SCR particulate filter (15) in the direction of exhaust gas flow, wherein the SCR particulate filter (15) can be continuously regenerated using nitrogen dioxide as an oxidizing agent.wherein at least one SCR catalyst element (19) is arranged downstream of the SCR particulate filter (15), by means of which nitrogen oxides also contained in the exhaust gas (9) of the internal combustion engine (5) can be reduced with ammonia as a reducing agent, and wherein a second reducing agent supply device (26) is provided, by means of which the reducing agent, in particular in the form of an aqueous urea solution, can be introduced into the exhaust stream (7) downstream of the SCR particulate filter (15) and upstream of the SCR catalyst element (19). According to the invention, a control unit (25) is provided, by means of which the amount of reducing agent introduced into the exhaust stream (7) by means of the first reducing agent supply device (22) and/or the amount of reducing agent introduced into the exhaust stream (7) by means of the second reducing agent supply device (26) is regulated and/or controlled as a function of the temperature (TSCR-PF) of the SCR particulate filter (15).