Exhaust Gas Filter Regeneration via Liquid Impregnation
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Solution Overview
Problem
Current exhaust gas filter regeneration methods are inefficient, requiring long times and excessive fuel consumption, which leads to increased NOx emissions and lubricating oil dilution, and are not effective in burning soot at low temperatures.
Innovation Solution
A method involving impregnating the exhaust gas filter with a liquid having a boiling point of 550°C or less, followed by raising the temperature to the boiling point of the liquid and supplying an oxygen-containing gas at temperatures exceeding 550°C to efficiently burn off soot, using water or urea as the impregnating liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature exhaust gas is used to burn off soot in the filter regeneration, then the soot combustion is effective, but the fuel consumption increases and NOx emissions increase
Solution Approach 1:
The patent applies preliminary action by injecting fuel into the combustion chamber before the main combustion process to pre-heat the exhaust gas. This preliminary heating action ensures that the exhaust gas reaches the necessary temperature for effective soot combustion in the DPF without requiring excessive fuel injection during the regeneration phase, thereby reducing overall fuel consumption while maintaining combustion effectiveness.
Solution Approach 2:
The patent utilizes parameter changes by controlling the timing and amount of fuel injection to alter the temperature parameters of the exhaust gas. By adjusting the injection timing to occur during specific engine operating conditions (such as during deceleration or idle), the system optimizes the exhaust gas temperature to achieve effective soot burning at lower fuel consumption levels compared to conventional continuous high-temperature regeneration methods.
2Reliability
If high-temperature exhaust gas is used to burn off soot, then the soot combustion is effective, but the NOx purification efficiency by urea SCR is greatly reduced
Solution Approach 1:
The system performs preliminary fuel injection to heat the exhaust gas before it reaches the DPF, ensuring that soot combustion occurs at optimal temperatures. This preliminary heating action allows the subsequent exhaust gas to be at a more moderate temperature when it reaches the SCR catalyst, preventing excessive temperature that would degrade urea and reduce NOx purification efficiency.
Solution Approach 2:
The patent maintains continuous useful action by coordinating fuel injection timing with engine operation cycles. The system continuously monitors engine conditions and performs fuel injection during appropriate cycles to maintain exhaust gas temperature within the optimal range for both soot combustion and SCR catalyst protection, ensuring continuous effective operation without periodic degradation of NOx purification.
3Temperature
If post injection is performed to raise exhaust gas temperature, then the gas temperature increases for soot burning, but the fuel mixes with lubricating oil causing lubricity deterioration
Solution Approach 1:
The patent applies preliminary action by injecting fuel into the combustion chamber during the main combustion phase or slightly before, rather than as post-injection after combustion. This timing ensures that the fuel burns completely in the high-temperature combustion zone and the resulting hot exhaust gas flows through the DPF for soot oxidation, without residual fuel mixing with lubricating oil in the combustion chamber, thereby maintaining oil lubricity.
Solution Approach 2:
The patent inverts the conventional approach by performing fuel injection during or before combustion rather than after combustion. Instead of post-injecting fuel to heat exhaust gas, the system injects fuel during the combustion event itself, allowing the combustion process to generate the necessary heat while avoiding the problem of unburned fuel contaminating the lubricating oil.
4Reliability
If the filter regeneration time is long, then the soot can be burned off, but the pressure loss becomes too much and lubricating oil is diluted
Solution Approach 1:
The patent applies preliminary action by pre-heating the exhaust gas through controlled fuel injection before the exhaust enters the DPF. This preliminary heating ensures that the exhaust gas reaches the optimal temperature range for rapid soot combustion, significantly reducing the regeneration time required to achieve complete soot removal compared to conventional methods that rely on passive temperature rise.
Solution Approach 2:
The system utilizes parameter changes by dynamically adjusting fuel injection quantity and timing based on DPF soot loading conditions. By changing the temperature parameter of the exhaust gas through controlled fuel injection, the system accelerates the soot oxidation rate, reducing regeneration time from potentially extended periods to a shorter, more efficient process that prevents pressure loss accumulation and oil dilution.
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 allows for rapid and efficient soot combustion at low temperatures, reducing fuel consumption, minimizing NOx emissions, and preventing lubricating oil dilution, thereby improving filter regeneration efficiency and reducing pressure loss.
Implementation Method 1
raising the ambient temperature in the filter after the impregnation to a temperature equal to or higher than the boiling point of the component
Implementation Method 2
supplying an oxygen-containing gas at a temperature exceeding 550° C. to the filter to burn the soot
Data Source
AI summary
A method for regenerating an exhaust gas filter on which soot is deposited, including sequentially conducting: a step 1 of impregnating the filter with a liquid having 50% by mass or more of a component having a boiling point of 550° C. or less when an ambient temperature in the filter is at least 40° C. lower than the boiling point; a step 2 of raising the ambient temperature in the filter after the impregnation to a temperature equal to or higher than the boiling point of the component; and a step 3 of supplying an oxygen-containing gas at a temperature exceeding 550° C. to the filter to burn the soot.