SCR Catalyst Secondary Emission Reduction Filter
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Solution Overview
Problem
Current SCR systems face issues with secondary emissions of catalytic material and ammonia slip, and existing DPF diagnostic techniques are inadequate for diagnosing loading and filtration efficiency.
Innovation Solution
A system comprising an exhaust aftertreatment system with a secondary emission reduction device downstream of the SCR catalyst, which includes a filter to capture secondary emissions and ammonia slip, and a controller for onboard diagnostic capabilities using differential pressure sensors to detect failures in the diesel particulate filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium based SCR catalysts are used to reduce NOx emissions, then NOx reduction efficiency is improved, but secondary emissions of catalytic material increase
Solution Approach 1:
A substrate is introduced as an intermediary component between the vanadium-based SCR catalyst and the exhaust stream. The substrate captures and retains volatized catalytic material, preventing its release as secondary emissions while maintaining the catalyst's NOx reduction functionality. This resolves the contradiction by providing a physical barrier that intercepts harmful material before it enters the environment.
Solution Approach 2:
The substrate employs porous material structure with controlled pore sizes and surface area to effectively trap volatized catalytic material. The porous architecture provides high surface area for capture while allowing exhaust gases to pass through, enabling the system to maintain catalytic activity while preventing secondary emissions of vanadium and other catalyst components.
2Reliability
If SCR systems are designed to maximize NOx reduction, then emission control performance is improved, but ammonia slip increases
Solution Approach 1:
The substrate acts as an intermediary that also addresses ammonia slip by providing additional surface area and catalytic activity. The substrate can facilitate further reactions of excess ammonia with NOx or promote ammonia oxidation, thereby reducing ammonia slip while maintaining the primary SCR system's NOx reduction performance.
3Object-generated harmful factors
If diesel particulate filter is used upstream of SCR catalyst, then particulate matter filtration is improved, but diagnostic capability of DPF loading and filtration efficiency remains inadequate
Solution Approach 1:
A differential pressure sensor is implemented to provide real-time feedback on the pressure drop across the DPF. This feedback mechanism enables continuous monitoring of DPF loading conditions and filtration efficiency, transforming the previously inadequate diagnostic capability into a robust monitoring system that provides actionable information about DPF status and performance.
Solution Approach 2:
The patent replaces inadequate mechanical or manual diagnostic methods with a electronic sensing system. The differential pressure sensor electronically measures and reports DPF conditions, substituting crude mechanical indicators with precise electronic measurement and diagnostics, thereby enabling accurate real-time monitoring of DPF loading and efficiency.
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 effectively reduces secondary emissions and provides accurate diagnostic capabilities for diesel particulate filter conditions, enhancing environmental compliance and operational efficiency.
Implementation Method 1
which includes a filter to capture secondary emissions and ammonia slip
Implementation Method 2
a controller for onboard diagnostic capabilities using differential pressure sensors to detect failures in the diesel particulate filter
Implementation Method 3
SCR systems adsorb ammonia (NH3) on a catalyst and then react the NH3 with NOx to reduce the NOx emissions
Implementation Method 4
SCR systems adsorb ammonia (NH3) on a catalyst
Data Source
AI summary
System and methods for reducing secondary emissions in an exhaust stream from an internal combustion engine are disclosed. The systems and methods include a filtration device positioned downstream from an SCR catalyst of an aftertreatment system disposed in the exhaust system. The filtration device can also be used for particulate filter diagnostics and for treatment of ammonia slip.