Ammonia Storage Model Temperature Gradient Correction
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Solution Overview
Problem
Exhaust treatment systems face inefficiencies in reducing NOx emissions due to slow reduction reaction rates and excess ammonia slipping from Selective Catalytic Reduction (SCR) devices, leading to environmental emissions.
Innovation Solution
An exhaust gas treatment system with a control module that predicts SCR device temperature and adjusts reductant injection based on a reductant load model, determining and correcting for reductant slip to optimize NOx reduction and minimize ammonia emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the SCR device operates at higher temperatures to accelerate the reduction reaction rate, then the NOx reduction efficiency is improved, but the ammonia slip increases due to excessive thermal energy causing reductant to escape
Solution Approach 1:
The patent applies dynamics by making the reductant injection rate adjustable and adaptive rather than fixed. The control module continuously modifies the injection rate based on real-time temperature measurements and reductant storage model predictions, allowing the system to optimize the balance between reaction efficiency and ammonia slip prevention under varying operating conditions
Solution Approach 2:
The patent implements feedback control by using temperature sensors to monitor SCR device temperature and feeding this information back to the control module. The control module then adjusts the reductant injection rate based on this feedback, creating a closed-loop control system that dynamically optimizes NOx reduction while minimizing ammonia slip
2Quantity of substance
If the reductant injection rate is increased to ensure sufficient reductant for NOx reduction, then the NOx reduction capacity is improved, but the ammonia slip increases when the reaction rate is slow or temperature is inappropriate
Solution Approach 1:
The patent applies preliminary action by using a reductant storage model to predict the amount of reductant stored in the SCR device before actual injection decisions are made. The control module uses this prediction to proactively adjust the injection rate, preventing both reductant deficiency and excess injection that would cause ammonia slip
Solution Approach 2:
The patent changes the injection rate parameter dynamically based on temperature and predicted reductant storage conditions. Rather than using a fixed injection rate, the system adjusts this parameter in real-time to match actual operating conditions, optimizing the balance between ensuring sufficient reductant for NOx reduction and preventing ammonia slip
3Ease of operation
If a fixed reductant load model is used to control injection, then the system operation is simplified, but the accuracy of reductant injection control decreases under varying temperature conditions
Solution Approach 1:
The patent transforms the static reductant load model into a dynamic model that adapts to varying temperature conditions. The control module continuously updates injection predictions based on real-time temperature data and rate of change, maintaining operational simplicity while significantly improving injection accuracy under varying conditions
Solution Approach 2:
The patent uses preliminary temperature measurement and rate of change calculation to predict future SCR device temperature conditions. This allows the system to proactively adjust the reductant injection rate before temperature deviations affect injection accuracy, maintaining both simplicity and precision
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 NOx emissions by precisely controlling reductant injection, minimizing ammonia slip and enhancing the overall efficiency of the SCR process.
Implementation Method 1
The SCR devices make use of NH3 to reduce the NOx. For example, when the proper amount of NH3 is supplied to the SCR device under the proper conditions, the NH3 reacts with the NOx in the presence of an SCR device to reduce the NOx emissions.
Data Source
AI summary
An exhaust gas treatment system includes a SCR device that stores a reductant that reacts with the NOx emissions and a reductant supply system to inject the reductant according to a reductant load model. At least one temperature sensor or model generates a temperature signal indicating an SCR temperature of the SCR device. The exhaust gas treatment system further includes a control module in electrical communication with the reductant supply system. The control module is configured to determine an amount of reductant that slips from the SCR device based on the at least one temperature signal and the rate of change of the SCR temperature. The control module further determines a correction factor based on the amount of slipped reductant to modify the reductant load model.