Dual-Step Regeneration Control for Simultaneous NOx-PM Reduction
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Solution Overview
Problem
Current diesel engine exhaust gas purification systems face challenges in efficiently regenerating catalytic particulate filters (CPF) and lean NOx traps (LNT), leading to reduced regeneration efficiency, support damage, and increased fuel consumption due to inadequate temperature control and regeneration methods that do not account for trapped PM amounts.
Innovation Solution
A system utilizing sensors to monitor exhaust gas temperature, differential pressure, and NOx levels, with a control unit that performs controlled fuel injections to manage regeneration based on predetermined conditions, including temperature ranges and PM amounts, to optimize CPF and LNT regeneration processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the interior temperature of DPF is increased to improve regeneration efficiency, then PM removal efficiency is improved, but the risk of support damage increases due to uncontrolled temperature rise
Solution Approach 1:
The patent implements dynamic temperature control by adjusting fuel injection timing and amount based on real-time monitoring of DPF interior temperature and trapped PM amount. The system transitions from static temperature maintenance to dynamic adjustment, allowing the temperature to be optimized for regeneration efficiency while preventing excessive temperature rise that could damage the support structure.
Solution Approach 2:
The system changes operational parameters (fuel injection timing, injection amount, air-fuel ratio) based on the trapped PM amount detected by differential pressure sensors. When PM amount is high, the system adjusts parameters to achieve higher temperatures for efficient regeneration; when PM amount is low, parameters are adjusted to maintain lower temperatures that prevent support damage.
2Productivity
If fuel post-injection amount is increased to raise DPF interior temperature, then regeneration efficiency is improved, but LNT degradation accelerates due to excessive heat exposure
Solution Approach 1:
The patent applies different temperature conditions to different components based on their thermal tolerance. The DPF receives high temperature for efficient PM regeneration, while the LNT is protected from excessive heat by controlling the air-fuel ratio and fuel injection timing. This localized quality approach allows each component to operate under optimal conditions for its specific function and material properties.
Solution Approach 2:
The system dynamically adjusts the air-fuel ratio and fuel injection timing based on real-time monitoring of LNT state and DPF temperature. When LNT regeneration is performed, the system controls the air-fuel ratio to prevent excessive temperature rise that would degrade the LNT catalyst, while still maintaining sufficient temperature for PM oxidation in the DPF.
3Reliability
If regeneration is performed frequently to prevent PM accumulation, then PM trapping capacity is maintained, but fuel consumption increases due to repeated regeneration cycles
Solution Approach 1:
The system uses differential pressure sensors to continuously monitor the trapped PM amount in the DPF and provides feedback to the control unit. Based on this feedback, the system determines the optimal regeneration timing and intensity, performing regeneration only when necessary to maintain PM trapping capacity, thereby avoiding unnecessary fuel consumption from frequent regeneration cycles.
Solution Approach 2:
The patent implements partial regeneration strategies where the degree and intensity of regeneration are adjusted according to the actual trapped PM amount. Instead of performing full regeneration cycles regardless of PM load, the system applies only the necessary regeneration action to maintain optimal PM trapping capacity, reducing fuel consumption while ensuring reliability.
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 enhances regeneration efficiency, prevents support damage, and reduces fuel consumption by tailoring regeneration strategies to specific PM loads, ensuring effective and durable operation of CPF and LNT components.
Implementation Method 1
a catalytic particulate filter (CPF) for trapping a particulate matter (PM) of the engine
Implementation Method 2
an interior temperature of the DPF is maintained at about 550° C. by raising the exhaust gas temperature by fuel post-injection of the engine, and the trapped PM in the DPF is burned by the heat of the exhaust gas
Implementation Method 3
a DeNOx catalyst for decomposition or reduction of the NOx under an excess oxygen atmosphere
Implementation Method 4
a first exhaust gas temperature sensor detecting a temperature of an exhaust gas of the engine; a second exhaust gas temperature sensor detecting a temperature of an exhaust gas flowing between the LNT and the CPF
Implementation Method 5
a differential pressure sensor detecting a pressure difference across the simultaneous NOx-PM reduction apparatus
Data Source
AI summary
The present invention provides a method for controlling regeneration of the simultaneous NOx-PM reduction apparatus having a lean NOx trap (LNT) for removing nitrogen oxide (NOx) an engine and a catalytic particulate filter (CPF) for trapping a particulate matter (PM) of the engine. According to an exemplary method, depending on the trapped PM amount in the CPF, the simultaneous NOx-PM reduction apparatus is regenerated according to a dual step regeneration including a mild regeneration at a low CPF interior temperature and a strong regeneration at a high CPF interior temperature.