Sulfur Suppressing Filter for Diesel Exhaust Aftertreatment
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Solution Overview
Problem
Conventional exhaust aftertreatment systems face challenges in reducing sulfur oxides (SOx) levels, particularly sulfur trioxide (SO3), which can react with ammonia, reducing its availability for NOx decomposition and affecting filtering efficiency and catalyst performance.
Innovation Solution
Incorporating a sulfur suppressing compound in filters positioned upstream and/or downstream of the selective catalytic reduction (SCR) system to reduce SOx levels by suppressing the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3), using catalysts like iron oxide and calcium oxide, and integrating these compounds into existing filter designs without significant modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxidation of SO2 is promoted to convert sulfur dioxide to sulfur trioxide, then sulfur conversion efficiency is improved, but SO3 content increases which reduces ammonia availability for NOx decomposition and poisons catalysts
Solution Approach 1:
The patent changes the chemical parameters of the filter by incorporating specific sulfur suppressing compounds (such as iron oxide, calcium oxide, or zinc oxide) that modify the oxidation behavior of SO2. These compounds alter the reaction conditions to prevent excessive SO3 formation while still achieving sulfur conversion, thereby resolving the contradiction between conversion efficiency and harmful SO3 generation.
Solution Approach 2:
The sulfur suppressing compounds act as intermediary substances within the filter that mediate the oxidation process. Instead of direct oxidation of SO2 to SO3, the intermediary compounds facilitate sulfur conversion through alternative pathways or controlled oxidation, reducing the formation of harmful SO3 while maintaining conversion efficiency.
2Device complexity
If conventional filters are used without sulfur suppressing compounds, then filter结构简单性 is maintained, but SOx gases are not effectively reduced and ammonia is consumed by SO3 formation
Solution Approach 1:
The patent merges the sulfur suppression function with the existing filter structure by incorporating sulfur suppressing compounds directly into the filter medium or as a coating on the filter elements. This integration allows the filter to perform both particulate filtration and sulfur suppression functions simultaneously, maintaining structural simplicity while improving reliability by preserving ammonia for NOx decomposition.
Solution Approach 2:
The filter is designed to serve multiple functions: particulate matter filtration, SO2 oxidation control, and sulfur suppression. By making the filter multi-functional through the addition of sulfur suppressing compounds, the system maintains device simplicity while enhancing reliability, as the same filter component addresses multiple issues including ammonia preservation.
3Power
If higher sulfur content fuel is used to increase energy density, then energy output is improved, but SO3 formation increases which reduces filtering efficiency and poisons oxidation catalysts
Solution Approach 1:
The patent converts the harmful effect of sulfur-containing fuel into a beneficial outcome by using the sulfur suppressing compounds to capture and neutralize SOx gases. The high sulfur content fuel provides energy output, while the sulfur suppressing compounds in the filter convert the harmful SO3 into less harmful substances, thereby maintaining filtering efficiency and catalyst performance despite using higher sulfur fuel.
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 reduces SOx levels, maintains ammonia availability for NOx decomposition, and minimizes the negative impact on particulate sensors and oxidation catalysts, enhancing overall aftertreatment system efficiency.
Implementation Method 1
Oxidation of SO2 present in the exhaust gas can lead to an increase in SO3 content of the exhaust gas, e.g. due to oxidation of SO2 to SO3
Implementation Method 2
The filter comprises a sulfur suppressing compound formulated to reduce an amount of SOx gases included in the exhaust gas flowing through the aftertreatment system
Implementation Method 3
certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) catalyst to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3)
Data Source
AI summary
An aftertreatment system comprises a SCR system including a catalyst formulated to decompose constituents of an exhaust gas passing therethrough. A filter is positioned upstream of the SCR system. The filter comprises a sulfur suppressing compound formulated to reduce an amount of SOx gases included in the exhaust gas flowing through the aftertreatment system. In particular embodiments, the filter comprises a filter housing and a filter element positioned within the filter housing. The filter element comprises the sulfur suppressing compound.