NOx Storage-Reduction Catalyst Desulfurization with Exhaust Closure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing NOx storage-reduction catalysts accumulate sulfur components, reducing their NOx storage capacity, and methods like sulfur removal processes allow unintended hydrocarbon and carbon monoxide to escape.
Innovation Solution
A desulfurization method involving warming up the NOx storage-reduction catalyst, controlling the engine to a rich-burn mode, stopping the engine, and closing the exhaust passage downstream of the catalyst to prevent hydrocarbon and carbon monoxide leakage while using a reducing agent to remove sulfur components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfur removal process is performed by making the air-fuel ratio rich at high load, then sulfur components are removed from the catalyst, but hydrocarbon and carbon monoxide escape to the outside
Solution Approach 1:
The patent extracts the sulfur removal function from the high-load driving condition by performing desulfurization during engine idling or low-load operation. The exhaust passage is closed to create a separate desulfurization cycle, allowing sulfur removal without affecting normal vehicle operation and preventing harmful emissions during regular driving.
Solution Approach 2:
The patent introduces an exhaust passage closing mechanism as an intermediary to control exhaust flow. By closing the exhaust passage during desulfurization, the system creates a controlled environment where reducing agents can effectively remove sulfur without releasing hydrocarbons and carbon monoxide to the atmosphere.
2Reliability
If the engine operates continuously for sulfur removal, then sulfur components are reduced, but fuel consumption increases and vehicle operation is interfered with
Solution Approach 1:
The patent implements periodic desulfurization cycles during engine idling or low-load operation rather than continuous operation. The exhaust passage is closed for a predetermined period to allow sulfur removal, then opened to resume normal operation. This periodic approach maintains catalyst performance without continuously interfering with vehicle productivity.
Solution Approach 2:
The system utilizes the engine's own exhaust gases and idle operation to perform desulfurization without requiring separate fuel injection or external energy input. The reducing agents already present in the exhaust stream are used to remove sulfur, making the process self-sufficient and minimizing impact on overall vehicle operation.
3Reliability
If the air-fuel ratio is made rich for sulfur removal, then sulfur components are removed from the catalyst, but the amount of reducing agent required increases
Solution Approach 1:
The patent changes the operating parameters by performing desulfurization at lower engine loads or during idling rather than at high load. This parameter change allows effective sulfur removal using the naturally present exhaust gases without requiring excessive fuel injection, thereby reducing reducing agent consumption while maintaining removal effectiveness.
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
Effectively removes sulfur components from the NOx storage-reduction catalyst, preventing reducing agent leakage and maintaining catalyst efficiency without interfering with vehicle operation.
Implementation Method 1
The NOx storage-reduction catalyst removes NOx from exhaust gas by storing NOx while the air-fuel ratio of the engine is lean
Implementation Method 2
NOx is removed from the NOx storage-reduction catalyst by performing an NOx removal process at a predetermined timing. The NOx removal process is a process for desorbing NOx from the NOx storage-reduction catalyst and reducing NOx by making the air-fuel ratio of the engine lower (richer) than a theoretical air-fuel ratio when the temperature of the NOx storage-reduction catalyst is higher than or equal to the desorption temperature of NOX
Implementation Method 3
The NOx storage-reduction catalyst not only stores NOx in exhaust gas but also unintendedly stores sulfur components included in fuel or lubricant
Implementation Method 4
controlling the engine so that an excess air ratio of the engine becomes a target value that is lower than 1 when a temperature of the NOx storage-reduction catalyst reaches a temperature at which the NOx storage-reduction catalyst is capable of reducing sulfur components stored in the NOx storage-reduction catalyst
Data Source
AI summary
A desulfurization method includes: operating an engine to warm up an NOx storage-reduction catalyst provided in an exhaust passage coupled to the engine; controlling the engine so that an excess air ratio of the engine becomes a target value that is lower than 1 when a temperature of the NOx storage-reduction catalyst reaches a temperature at which the NOx storage-reduction catalyst is capable of reducing sulfur components stored in the NOx storage-reduction catalyst; stopping the engine; and closing the exhaust passage at a downstream side of the NOx storage-reduction catalyst.