Dynamic NOx Setpoint Adjustment for Diesel Exhaust Depollution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for reducing NOx emissions from diesel engines, such as selective catalytic reduction, face challenges when operating in low temperatures, leading to excessive reducing agent usage that can exceed device limits and reduce system lifespan.
Innovation Solution
A method that dynamically adjusts the NOx setpoint based on outside temperature, using a computer system to measure actual NOx production and inject a reducing agent compatible with physical limits, ensuring compliance with emission standards while prolonging system durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If selective catalytic reduction is used to treat NOx emissions, then NOx removal efficiency is improved, but reducing agent consumption increases excessively in low temperature conditions
Solution Approach 1:
The patent implements dynamic adjustment of the reducing agent injection rate based on real-time operating conditions (temperature, load, air-to-fuel ratio). The control system continuously adapts the injection rate to match actual NOx production, preventing excessive consumption during cold operation while maintaining effective NOx removal during normal operation.
Solution Approach 2:
The patent changes the control parameter from a fixed injection rate to a variable injection rate that responds to operating conditions. By monitoring temperature and other parameters, the system adjusts the reducing agent injection rate to optimize the balance between NOx removal efficiency and reducing agent consumption.
2Object-generated harmful factors
If large flows of reducing agent are injected to treat high NOx production in low temperatures, then NOx removal efficiency is improved, but device lifespan is reduced
Solution Approach 1:
The system dynamically adjusts the reducing agent injection rate based on actual operating conditions rather than using a fixed high rate. This prevents unnecessary exposure of the catalyst to excessive reducing agent flows that would accelerate degradation, thereby extending device lifespan while maintaining NOx removal effectiveness.
Solution Approach 2:
The control system uses feedback from sensors monitoring temperature, load, and air-to-fuel ratio to adjust the reducing agent injection rate in real-time. This closed-loop control ensures the injection rate matches actual NOx production, preventing excessive reducing agent exposure that would harm the catalyst and reduce its lifespan.
3Productivity
If reducing agent injection is controlled to match stoichiometric proportions, then treatment efficiency is improved, but system complexity increases due to instantaneous NOx measurement requirements
Solution Approach 1:
The control system uses readily available sensor data (temperature, load, air-to-fuel ratio) that are already part of the engine management system to determine reducing agent injection rates. This approach avoids the need for additional instantaneous NOx measurement devices, reducing system complexity while maintaining effective treatment through self-service utilization of existing system data.
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 NOx emissions while extending the lifespan of depollution devices by optimizing reducing agent usage according to temperature-dependent NOx production, ensuring compliance with emission standards and reducing agent consumption.
Implementation Method 1
The removal of NOx from the exhaust gases can be carried out by different methods... treatment of the nitrogen oxides... at least partially implemented in a catalyst disposed in the exhaust line
Implementation Method 2
selective catalytic reduction which consists of injecting a NOx reducing solution... 4NH3 + 4NO + O2 → 4N2 + 6H2O... 2NH3 + NO + NO2 → 2N2 + 3H2O
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for depolluting exhaust gases from an engine comprising an exhaust line, this depollution method being at least partially implemented in a catalyst, and comprising the steps of: - determining a quantity of nitrogen oxides actually produced by the engine, - determining a setpoint for the quantity of nitrogen oxides in the exhaust gases not to be exceeded at the exhaust outlet, - comparing the quantity of nitrogen oxides actually produced with this setpoint, and if the quantity of nitrogen oxides actually produced by the engine is greater than this setpoint, treating the nitrogen oxides, as long as the quantity of nitrogen oxides actually produced is greater than the setpoint, characterized in that the setpoint is determined as a function of the outside temperature.