Dual-Position SCR Reducing Agent Injection for NOx Conversion
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Solution Overview
Problem
Existing SCR catalytic converter systems face inefficiencies in nitrogen oxide reduction due to excessive reducing agent consumption and NH3 slip, particularly when operating temperatures and load conditions vary, leading to suboptimal NOx conversion and increased reducing agent usage.
Innovation Solution
The method employs two injection positions for the reducing agent, with injection primarily via the second metering device when the SCR-coated particulate filter temperature exceeds a threshold, allowing for efficient downstream supply to the SCR catalytic converter, and predominantly via the first metering device during engine start-ups, optimizing NOx conversion and reducing agent usage based on specific operating states and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reducing agent is injected upstream of the SCR-coated particulate filter, then NOx conversion is improved, but reducing agent consumption increases and NH3 slip occurs
Solution Approach 1:
The patent divides the reducing agent injection system into two separate injection positions: a first injection position upstream of the SCR-coated particulate filter and a second injection position downstream of the particulate filter but upstream of the SCR catalytic converter. This segmentation allows independent control of reducing agent delivery to different components, preventing excessive consumption and NH3 slip while ensuring sufficient reducing agent availability for NOx conversion.
Solution Approach 2:
The control method dynamically switches between the first and second injection positions based on real-time operating conditions, including temperature thresholds and load conditions. The system adapts the injection strategy from static to dynamic, selecting the optimal injection position to minimize reducing agent consumption while maintaining effective NOx reduction.
2Productivity
If reducing agent is injected upstream of the SCR catalytic converter, then NOx conversion is improved, but NH3 slip increases
Solution Approach 1:
By separating the injection system into two independent injection positions, the patent enables precise control over reducing agent delivery. The second injection position allows direct supply of reducing agent to the SCR catalytic converter without excessive NH3 slip, while the first injection position can be used when NOx conversion is the priority.
Solution Approach 2:
The control method uses feedback from temperature sensors and load conditions to dynamically adjust which injection position is active. This feedback mechanism prevents NH3 slip by selecting the appropriate injection position based on real-time system state, ensuring optimal balance between NOx conversion and NH3 management.
3Productivity
If the SCR-coated particulate filter temperature is high, then regeneration is improved, but reducing agent availability for NOx conversion decreases
Solution Approach 1:
The system dynamically adjusts the injection strategy based on the temperature of the SCR-coated particulate filter. When temperature exceeds a threshold indicating active regeneration, the control method switches to the second injection position to ensure reducing agent is delivered directly to the SCR catalytic converter, maintaining NOx conversion capability during regeneration phases.
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 minimizes reducing agent consumption while maintaining effective NOx reduction, even during regeneration phases of the particulate filter, by strategically switching between injection positions based on temperature and operational conditions, ensuring efficient exhaust gas aftertreatment.
Implementation Method 1
an SCR (Selective Catalytic Reduction) catalytic converter is arranged which reduces the nitrogen oxides (NOx) contained in the exhaust gas of the internal combustion engine to form nitrogen in the presence of a reducing agent
Implementation Method 2
The NOx conversion in the SCR catalytic converter is more successful, the greater the amount of reducing agent in the catalytic converter
Implementation Method 3
In an operating state, in which the temperature of the SCR-coated particulate filter lies above a predefinable threshold value, injection of liquid reducing agent is performed substantially via the second injection position
Data Source
AI summary
In a method for operating an SCR catalytic converter system of an internal combustion engine, the SCR catalytic converter system comprises at least one SCR catalytic converter (30) and at least one upstream SCR-coated particulate filter (20). In order to inject liquid reducing agent for the SCR catalytic converter (30) and/or for the SCR-coated particulate filter (20), a first injection position is provided upstream of the SCR-coated particulate filter (20) in the form of a first metering device (40) and a second injection position is provided upstream of the SCR catalytic converter (30) and downstream of the SCR-coated particulate filter (20) in the form of a second metering device (50). The injection positions for the injection of liquid reducing agent are selected in a manner which is dependent on the operating states of the SCR catalytic converter system.