Diesel Exhaust Fluid Additive for SCR Deposit Reduction
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Solution Overview
Problem
Diesel engines face challenges in reducing NOx emissions due to the formation of white crystalline deposits in exhaust systems when using diesel exhaust fluid (DEF) with Selective Catalytic Reduction (SCR) systems, which complicates maintenance and efficiency.
Innovation Solution
An aqueous solution comprising an adduct of an α-substituted succinic anhydride with a polyalkylene glycol or its derivative, capable of releasing ammonia above 150 °C, is used to vaporize and inhibit deposit formation in exhaust systems, effectively reducing or preventing the formation of deposits on surfaces within the SCR system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If diesel exhaust fluid (DEF) is used with Selective Catalytic Reduction (SCR) systems to reduce NOx emissions, then NOx emission levels are reduced, but white crystalline deposits form on exhaust system surfaces
Solution Approach 1:
The patent introduces an intermediary substance (surfactant or detergent additive) that mediates between the DEF and the exhaust system surfaces. This additive prevents the harmful interaction that leads to deposit formation while maintaining the beneficial NOx reduction function of the SCR system.
Solution Approach 2:
The patent converts the harmful effect of DEF (which causes deposits) into a beneficial outcome by adding substances that transform the deposit-forming mechanism. The additives modify the chemical behavior of DEF to prevent crystalline deposit formation while preserving ammonia release for NOx reduction.
2Object-affected harmful factors
If conventional methods (mechanical scraping or component replacement) are used to remove deposits, then deposits are removed from surfaces, but maintenance complexity and costs increase
Solution Approach 1:
The patent applies preliminary action by preventing deposit formation in the first place through the use of additives in the DEF formulation. This proactive approach eliminates the need for subsequent mechanical scraping or component replacement, thereby reducing maintenance complexity.
Solution Approach 2:
The patent implements self-service by enabling the exhaust system to prevent its own fouling through chemically modified DEF. The additives continuously protect surfaces during normal operation, eliminating the need for external maintenance interventions.
3Object-generated harmful factors
If stricter NOx emission limits are enforced, then environmental compliance is improved, but engine efficiency and productivity may be compromised
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the DEF formulation. By adjusting the concentration and type of additives (surfactants/detergents), the system achieves both strict NOx emission compliance and maintained engine efficiency through optimized exhaust flow and ammonia release characteristics.
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 solution significantly reduces deposit formation by up to 40% over five hours, enhancing the operational efficiency and reducing maintenance costs by preventing the accumulation of deposits in the exhaust treatment system.
Implementation Method 1
vaporizing an exhaust after-treatment composition at about 150 °C or more to produce ammonia
Implementation Method 2
a compound capable of providing ammonia above about 150 °C
Data Source
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AI summary
Formulations of diesel exhaust fluid ("DEF") that include one or more functional additives and the use of such formulations for reducing deposits in the exhaust systems of engines that use DEF requiring Selective Catalytic Reduction ("SCR") catalysts are described.