Turbocharged Engine Oxidation Catalyst Regeneration
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Solution Overview
Problem
Lean burn gas engines emit high levels of hydrocarbons, primarily methane, which is a greenhouse gas, and existing oxidation catalysts for reducing these emissions often require high exhaust temperatures, leading to turbocharger damage during regeneration due to mechanical constraints.
Innovation Solution
Introducing gaseous fuel sequentially into an oxidation catalyst at multiple locations within the catalyst, combined with water injection and temperature monitoring, to achieve partial regeneration while maintaining exhaust temperatures below the turbocharger's limits, thereby preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is introduced into the exhaust system to regenerate the oxidation catalyst, then the catalyst regeneration is achieved, but the exhaust temperature exceeds the turbocharger's maximum temperature limit
Solution Approach 1:
The exhaust system is divided into multiple injection locations (first injection location upstream of the oxidation catalyst, second injection location downstream of the oxidation catalyst) to segment the fuel injection process. This allows controlled temperature increase at different zones, enabling catalyst regeneration while preventing excessive temperature rise that would damage the turbocharger.
Solution Approach 2:
Different injection locations are used to create local temperature zones: the first injection location creates a localized high-temperature zone for catalyst regeneration, while the second injection location downstream helps control and reduce the temperature before it reaches the turbocharger, ensuring local quality control throughout the exhaust system.
2Reliability
If the oxidation catalyst is arranged upstream from the turbocharger to enable methane oxidation, then the catalyst can operate at required temperatures, but the turbocharger is at risk of damage during catalyst regeneration
Solution Approach 1:
The system performs preliminary temperature control by injecting fuel at a second location downstream of the oxidation catalyst before the exhaust reaches the turbocharger. This preliminary action reduces the temperature and rotation speed of the exhaust gas before it enters the turbocharger, preventing damage while maintaining the catalyst's ability to oxidize methane.
Solution Approach 2:
The control unit continuously monitors exhaust temperature and turbocharger rotation speed, using this feedback to dynamically adjust fuel injection timing and quantity at both injection locations. This ensures the oxidation catalyst receives sufficient heat for methane oxidation while preventing excessive temperature and speed that would damage the turbocharger.
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 allows for effective regeneration of the oxidation catalyst while minimizing the risk of turbocharger damage by controlling exhaust temperatures and rotation speeds, ensuring efficient methane oxidation and reducing hydrocarbon emissions.
Implementation Method 1
an oxidation catalyst works only when the exhaust gas temperature is high enough, i.e. approximately 500 °C. The exhaust gas temperature after the engine is typically too low, often around 400 °C, for oxidation of methane.
Implementation Method 2
When the fuel burns, it raises the exhaust temperature enabling regeneration of the oxidation catalyst. Typically temperature of approximately 650-750 °C is needed for the regeneration.
Data Source
Figure 1~2
Figure 3~5
AI summary
A method for operating a turbocharged internal combustion engine (1), in which method gaseous fuel is introduced into an oxidation catalyst (3) sequentially in different locations for regenerating part of the oxidation catalyst (3) at a time. The invention also concerns an exhaust system for an internal combustion engine (1)and an oxidation catalyst (3).