NOx Adsorber Regeneration via Air-Fuel Ratio Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
NOx storage catalyst units in internal combustion engines face reduced storage capacity and catalytically active surface area due to the adsorption of SOx, necessitating a method for effective desulfurization (de-SOx) to regenerate the NOx adsorber.
Innovation Solution
An engine management system that controls the regeneration process of the NOx adsorber through a desulfurization process by selectively cycling the air-fuel ratio between lean and rich modes, using an after-treatment manager module and closed-loop control to maintain the adsorber's temperature at 650°C, ensuring efficient removal of sulfur and regeneration of the NOx adsorber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the NOx adsorber operates continuously to store NOx, then the NOx storage capacity is improved, but the sulfur accumulation reduces the storage capacity and catalytic activity over time
Solution Approach 1:
The system implements periodic regeneration cycles where the air-fuel ratio is switched between lean mode (for NOx storage) and rich mode (for desulfurization). This periodic switching allows the adsorber to accumulate NOx during lean operation and then undergo desulfurization during rich operation, resolving the contradiction between continuous storage and long-term performance stability.
2Quantity of substance
If the adsorber is regenerated frequently to remove sulfur, then the storage capacity is maintained, but the engine operation complexity increases
Solution Approach 1:
The system changes the air-fuel ratio parameter as a control variable to achieve desulfurization. By switching the lambda value between lean (λ>1) and rich (λ<1) conditions, the system can regenerate the adsorber without adding physical components, thereby maintaining storage capacity while managing control complexity through parameter modulation.
Solution Approach 2:
The air-fuel ratio control system serves multiple functions: it controls engine power output, manages emissions during normal operation, and enables desulfurization during regeneration. This multi-functionality allows the same control mechanism to maintain adsorber capacity without requiring separate dedicated systems, thus avoiding increased device complexity.
3Productivity
If the air-fuel ratio is switched between lean and rich modes for desulfurization, then the sulfur removal efficiency is improved, but the energy consumption increases
Solution Approach 1:
The system uses periodic switching between lean and rich air-fuel ratios to achieve desulfurization. During lean operation, NOx is stored efficiently; during rich operation, sulfur is removed. This periodic action enables effective desulfurization while minimizing overall fuel consumption by limiting rich operation to necessary regeneration intervals rather than continuous operation.
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 regenerates the NOx adsorber by maintaining the required temperature and air-fuel ratio, enhancing its storage capacity and catalytic activity, thereby improving the overall exhaust treatment efficiency.
Implementation Method 1
NOx storage catalyst units or adsorbers are used to purify exhaust gases of combustion engines. These NOx storage catalyst units, in addition to storing or trapping NOx, also trap and store unwanted SOx in the form of sulfates.
Implementation Method 2
The process of regenerating NOx adsorbers varies depending on whether operating in a de-NOx mode (in which NOx is converted and removed from the unit) or a de-SOx mode (in which the unit is ran through a de-SOx process).
Implementation Method 3
A catalyst is a material that causes a chemical reaction to proceed at a usually faster rate without becoming part of the reaction process. The catalyst is not changed during the reaction process but rather converts the harmful pollutants into substances or gases that are not harmful to the environment.
Implementation Method 4
Emission filters in the exhaust gas systems of internal combustion engines are used to remove unburned soot particles from the exhaust gas and to convert harmful pollutants such as hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and oxides of sulfur (SOx) into harmless gases.
Data Source
AI summary
A system, method, and software for regenerating an adsorber connected with a flow of exhaust from an engine. An open-loop control module for ramping up and maintaining a temperature value of an adsorber to a regeneration temperature value by controlling an air fuel ratio value of an engine to operate at an open-loop controlled variable duty cycle. A closed-loop control module is operable to take control from the open-loop control module to maintain the adsorber at the regeneration temperature value if the temperature value of the adsorber deviates from the regeneration temperature value by controlling the air fuel ratio value of the engine to operate at a closed-loop controlled variable duty cycle.