Staged Diesel Particulate Filter Regeneration via NOx and Temperature Control
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Solution Overview
Problem
Current methods for regenerating diesel particulate filters often require high temperatures to burn off soot, which can lead to uncontrolled combustion and damage to the filter, and fail to manage soot loads efficiently, resulting in frequent regeneration needs and poor fuel economy.
Innovation Solution
A staged regeneration method that elevates the exhaust gas temperature to between 450°C and 550°C with high NOx and oxygen levels for a controlled burn, followed by a higher temperature phase to completely regenerate the filter, reducing the risk of uncontrolled combustion and extending soot-loading intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature is used to burn off soot, then regeneration effectiveness is improved, but risk of uncontrolled combustion and filter damage increases
Solution Approach 1:
The regeneration process is divided into multiple stages with different temperature ranges and NOx concentrations. The first stage uses moderate temperature (450-550°C) with high NOx to oxidize surface soot, while subsequent stages gradually increase temperature and decrease NOx to complete regeneration. This segmentation prevents uncontrolled combustion by controlling the oxidation rate at each stage.
Solution Approach 2:
Before applying high temperature, the method first introduces a preliminary oxidation stage with moderate temperature and high NOx concentration. This preliminary action removes a portion of the soot load and prepares the filter for the subsequent high-temperature stage, reducing the risk of uncontrolled combustion when high temperature is eventually applied.
2Reliability
If frequent regeneration is performed, then soot load management is improved, but fuel economy deteriorates
Solution Approach 1:
The method utilizes changes in NOx concentration and temperature parameters to enable effective regeneration at lower temperatures than traditional methods. By introducing high NOx concentrations (500-2000 ppm) during the regeneration process, the oxidation of soot is enhanced at moderate temperatures, allowing regeneration to occur without requiring excessive energy input and thus preserving fuel economy.
3Productivity
If high NOx concentration is used during regeneration, then soot oxidation rate is improved, but NOx emissions increase
Solution Approach 1:
The regeneration process uses periodic variation of NOx concentration and temperature. High NOx concentrations are applied intermittently during specific stages to maximize soot oxidation, followed by stages with lower NOx and higher temperature to complete regeneration. This periodic action achieves effective soot removal while limiting overall NOx emissions through temporal control.
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 method safely and efficiently reduces particulate matter in the filter, allowing for longer regeneration intervals and improved fuel economy by using lower initial temperatures for partial regeneration and higher temperatures for complete regeneration, thus enhancing filter management and energy utilization.
Implementation Method 1
burning the soot in the diesel particulate filter
Data Source
Figure 1~4
Figure 5
Figure 6A
AI summary
A method for regenerating a diesel particulate filter includes elevating a temperature of a gas stream flowing into an inlet of the diesel particulate filter to greater than or equal to 450° of the inlet of the diesel particulate filter, wherein the gas stream at the inlet of the diesel particulate filter contains an amount of NOx of equal to or greater than 300 ppm, and an amount of O2 of equal to or greater than 5 % volume, thereby burning the soot within the diesel particulate filter. The method also includes elevating a temperature of the gas stream flowing into the inlet of the diesel particulate filter to less than or equal to 550 °C at the inlet of the diesel particulate filter, wherein a burn rate of soot from porous walls of the diesel particulate filter is greater than or equal to 3.8 grams/liter/hour.