SCR Catalyst Reducing Agent Adsorption Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust gas purification systems for internal combustion engines face challenges in controlling the amount of reducing agent adsorbed on SCR catalysts to achieve a target NOx purification ratio, leading to excessive reducing agent flow-out and desorption without consumption for NOx reduction.
Innovation Solution
An exhaust gas purification system that includes a control unit to adjust the reducing agent supply amount based on consumption and desorption rates, ensuring the reducing agent adsorption amount is maintained at a target level by adding a predetermined amount to the reduction consumption amount, and adjusting this amount according to temperature and NOx flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reducing agent supply amount is increased to maintain target adsorption level, then the NOx purification ratio is improved, but the amount of reducing agent flowing out without being adsorbed increases
Solution Approach 1:
The control unit calculates the adsorption amount of reducing agent on the SCR catalyst based on the supply amount and consumption amount, compares it with the target adsorption amount, and adjusts the supply amount accordingly. This closed-loop feedback control ensures the adsorption amount is maintained at the target level while optimizing the supply amount to minimize unnecessary flow-out of reducing agent.
Solution Approach 2:
The system uses the SCR catalyst's own adsorption characteristics and consumption patterns to determine the optimal supply amount. By calculating the adsorption amount from the difference between supply and consumption, the system enables the catalyst to regulate its own reducing agent levels without external intervention, minimizing waste while maintaining purification efficiency.
2Loss of substance
If the reducing agent supply amount is controlled precisely to match consumption, then the reducing agent flow-out is reduced, but the adsorption amount cannot be maintained at target level when desorption occurs
Solution Approach 1:
The control unit anticipates desorption by maintaining the adsorption amount at a target level that accounts for expected desorption losses. By calculating the adsorption amount based on supply minus consumption and comparing it with the target, the system proactively adjusts supply to compensate for upcoming desorption, ensuring the adsorption amount remains at the target level rather than merely reacting to desorption after it occurs.
3Reliability
If the amount of reducing agent adsorbed on the SCR catalyst is excessive, then the target NOx purification ratio can be achieved, but the amount of reducing agent flowing out without being adsorbed or consumed increases
Solution Approach 1:
The system dynamically adjusts the reducing agent supply amount based on calculated adsorption levels. By continuously monitoring the adsorption amount (supply minus consumption) and comparing it with the target adsorption amount, the control unit modulates the supply parameter to maintain adsorption at the optimal target level, avoiding both excessive and insufficient adsorption conditions.
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
This approach effectively controls the reducing agent adsorption amount on the SCR catalyst, preventing excessive flow-out and desorption, thereby maintaining the target adsorption level and optimizing NOx reduction efficiency.
Implementation Method 1
a selective reduction type NOx catalyst provided in an exhaust passage of the internal combustion engine which selectively reduces NOx contained in exhaust gas when a reducing agent is supplied thereto
Implementation Method 2
The reducing agent supplied to the SCR catalyst is adsorbed to the SCR catalyst. The reducing agent adsorbed on the SCR catalyst is then used to reduce the NOx.
Data Source
AI summary
An object of the present invention is to provide a technique with which an amount of reducing agent adsorbed to a selective reduction type NOx catalyst provided in an exhaust passage of an internal combustion engine can be controlled to a target adsorption amount. In an exhaust gas purification system for an internal combustion engine according to the present invention, when a reducing agent adsorption amount adsorbed on a selective reduction type NOx catalyst is held at a target adsorption amount, a reducing agent supply amount supplied from a supply apparatus per unit time is controlled to an amount obtained by adding a predetermined amount to a reduction consumption amount, which is an amount of reducing agent consumed per unit time by the selective reduction type NOx catalyst for NOx reduction.