Adapting Reductant Injection for Catalyst Aging
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Solution Overview
Problem
The effectiveness of catalysts in exhaust treatment systems for internal combustion engines decreases over time, leading to emissions exceeding compliance values, as the number and type of active sites on the catalysts' surface change due to operating conditions, resulting in reduced conversion performance.
Innovation Solution
A system that monitors catalyst performance by obtaining operating parameters such as engine run time, temperatures, and emission measurements to determine a deterioration factor, which is used to adjust the air-fuel ratio or reductant injection commands to account for catalyst degradation, thereby maintaining emissions compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the catalyst is used for extended operation, then the engine can operate longer, but the catalyst effectiveness decreases and emissions exceed compliance values
Solution Approach 1:
The system dynamically adjusts the reductant injection rate based on real-time catalyst effectiveness measurements. As catalyst performance degrades over time, the control system increases reductant injection to compensate, maintaining emissions compliance throughout the catalyst's extended service life rather than using a static injection rate.
Solution Approach 2:
The system implements a feedback loop where catalyst effectiveness is continuously measured (via NOX sensors upstream and downstream of the catalyst), and this measurement feeds back to the control system which adjusts the reductant injection rate accordingly. This closed-loop control maintains emissions compliance despite catalyst aging.
2Reliability
If the reductant injection rate is increased to compensate for catalyst deterioration, then emissions compliance is maintained, but reductant consumption increases
Solution Approach 1:
The reductant injection rate is dynamically adjusted to match the actual catalyst effectiveness. When the catalyst is fresh and highly effective, minimal reductant is injected. As the catalyst deteriorates, the injection rate increases only to the extent necessary to maintain compliance, avoiding excessive reductant consumption that would occur with a constantly high injection rate.
Solution Approach 2:
The system changes the reductant injection parameter (injection rate) based on catalyst age and measured effectiveness. This parameter adaptation allows the system to use the minimum necessary reductant amount at each stage of catalyst life, optimizing the balance between emissions compliance and reductant consumption.
3Adaptability or versatility
If the engine operates under varying conditions, then the engine is more versatile, but the catalyst deterioration rate becomes unpredictable
Solution Approach 1:
Rather than relying on predictions based on operating conditions, the system uses real-time feedback from NOX sensors to directly measure catalyst effectiveness. This actual measurement approach is more reliable than prediction models, as it directly reflects the catalyst's true performance regardless of how it got there, accommodating any operating condition history.
Solution Approach 2:
The system replaces mechanical/predictive modeling approaches (estimating catalyst life based on operating hours and conditions) with a sensor-based measurement approach. By using NOX sensors to directly measure catalyst performance, the system substitutes complex prediction algorithms with direct observation, achieving more accurate and reliable effectiveness assessment.
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
The system enables the engine to remain in emissions compliance for a longer duration by adapting controls based on catalyst performance, reducing the need for frequent maintenance and improving engine operation.
Implementation Method 1
engines (e.g., internal combustion engines such as reciprocating engines or gas turbines) combust a mixture of fuel and air to generate combustion gases... which may be subject to exhaust treatment systems that include one or more catalytic converters (e.g., three-way catalyst (TWC) assembly, selective catalytic reduction (SCR) assembly) to reduce the emissions of nitrogen oxides (NOX), hydrocarbons (HC), carbon monoxide (CO), and other emissions
Data Source
AI summary
A system includes an exhaust treatment system configured to treat emissions from a combustion engine via a catalyst. The system includes a controller configured to obtain an operating parameter indicating catalyst performance. The controller is configured to determine a deterioration factor indicating deterioration of the catalyst based at least in part on the operating parameter. The controller is configured to determine an adaptation term configured to modify a reductant injection command for the combustion engine to account for the deterioration factor of the catalyst. The controller is configured to generate a signal indicating the adaptation term.