Exhaust Gas Segmentation for Low-Load Particulate Reduction
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Solution Overview
Problem
Current technologies for reducing particulate matter emissions in internal combustion engines, particularly in large ships, are inadequate at low engine loads due to limitations in thermal regeneration of particulate abatement devices, leading to decreased performance and frequent maintenance needs.
Innovation Solution
A two-stroke internal combustion engine design with a separation device that separates exhaust gas into two streams, allowing only the hotter stream with higher particulate matter concentration to pass through a device for reducing particulate matter and an SCR reactor, while the cooler stream is diverted, enabling efficient oxidation and reduction of emissions even at low loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gas is directed through a particulate matter reduction device at low engine loads, then particulate matter reduction is attempted, but the temperature is insufficient for effective thermal regeneration and oxidation reactions
Solution Approach 1:
The exhaust gas flow is divided into multiple separate component exhaust lines, each handling a portion of the total exhaust flow. This segmentation allows the system to direct only the necessary amount of exhaust gas through the particulate matter reduction device, maintaining sufficient temperature for effective operation even at low engine loads, while reducing the overall size and cost requirements of the reduction device.
2Object-generated harmful factors
If a large SCR reactor is used to handle full load outflow rate, then nitrogen oxide reduction capacity is sufficient, but device complexity and cost increase
Solution Approach 1:
The exhaust treatment system is segmented into multiple component exhaust lines with separate SCR reactors or reduction devices for each line. Each SCR reactor handles only a portion of the total nitrogen oxide load, allowing the use of smaller, less complex, and more cost-effective reactors while maintaining sufficient overall reduction capacity at both low and high engine loads.
3Object-generated harmful factors
If a device for reducing particulate matter is installed, then particulate matter reduction is achieved, but maintenance measures are necessary at shorter intervals due to insufficient thermal regeneration
Solution Approach 1:
By dividing the exhaust flow into separate component exhaust lines and directing them through the particulate matter reduction device in a controlled manner, the system ensures sufficient temperature conditions for thermal regeneration are maintained even at low engine loads. This prevents particulate accumulation that would otherwise require frequent maintenance, thereby extending maintenance intervals and improving reliability.
Solution Approach 2:
The system utilizes the periodic nature of engine operation and the controlled routing of exhaust streams to periodically regenerate the particulate matter reduction device. By alternating or combining different exhaust line configurations, the system maintains regeneration conditions without requiring continuous high-temperature operation, thus extending maintenance intervals.
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 ensures reliable and flexible reduction of particulate emissions across varying engine loads by maintaining sufficient temperatures for oxidation reactions and reducing the size and cost of SCR reactors, enhancing fuel efficiency and extending maintenance intervals.
Implementation Method 1
The separation device is configured to separate the exhaust gas from each combustion chamber into a first gas stream for the first component exhaust line and a second gas stream for the second component exhaust line, wherein the temperature of the second gas stream is lower than the temperature of the first gas stream
Implementation Method 2
The regeneration of particulate matter abatement devices typically is based on oxidation of carbon based soot particles
Implementation Method 3
a first selective catalytic reduction (SCR) reactor may be arranged in the first component exhaust line downstream of the separation device
Data Source
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AI summary
The invention relates to an internal combustion engine (1). The internal combustion engine comprises at least two cylinders (2). Each of the two cylinders comprises a combustion chamber (3) and has an inlet for a fuel and an outlet (5) for an exhaust gas with an outlet valve (6). The engine comprises at least one separation device (7) downstream of the combustion chambers (3) for separating the exhaust gas of all combustion chambers (3) into a first and a second exhaust gas stream. A first (8) and a second exhaust line (9) are connected to the at least one separation device (7). The at least one separation device (7) is configured to separate the exhaust gas from the combustion chambers (3) into a first gas stream for the first component exhaust line (8) and a second gas stream for the second component exhaust line (9). A device for reducing particulate matter (10) is arranged in the first component exhaust line (8) downstream of the separation device (7). The separation device (7) is configured to separate the exhaust gas from the combustion chamber (3) into a first gas stream, preferably for the first component exhaust line (8), and a subsequent second gas stream, preferably for the second component exhaust line (9), wherein the temperature of the second gas stream is lower than the temperature of the first gas stream.