Radiation Receiver Urea Deposit Detection in SCR Exhaust
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Solution Overview
Problem
Current SCR systems face challenges in accurately detecting and preventing urea deposits in exhaust pipes, as existing methods are indirect, lack sensitivity, or are ineffective during low temperature conditions, leading to potential blockages and maintenance issues.
Innovation Solution
An apparatus and method utilizing a radiation receiver and electronic control unit within the exhaust pipe to detect urea deposits through changes in wave characteristics, with a control valve adjusting urea flow to prevent or remove deposits, and potentially increasing exhaust temperature to decompose and remove deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ammonia is injected into the exhaust in the form of aqueous urea to reduce NOx, then NOx reduction is achieved, but solid deposits form in the exhaust at unsuitable operating conditions
Solution Approach 1:
The radiation receiver continuously monitors the exhaust pipe for deposit formation before significant blockages occur. By detecting changes in radiation transmission caused by early-stage deposits, the system can take preventive action (adjusting urea injection or exhaust temperature) before the deposits reach harmful levels, thus maintaining NOx reduction efficiency while preventing blockages.
2Measurement precision
If thermal decomposition of deposits is used to detect deposits, then deposit detection is achieved, but the method is indirect and has limited accuracy especially during low temperature exhaust flow
Solution Approach 1:
The patent replaces the indirect thermal decomposition detection method with a direct optical detection method using radiation receivers. These receivers measure the transmission of radiation through the exhaust pipe, and deposits attenuate the radiation in a manner that can be quantified. This direct optical measurement provides accurate deposit detection regardless of exhaust temperature, eliminating the limitations of thermal decomposition-based methods.
3Reliability
If pressure drop measurement is used to detect deposits, then deposit detection is achieved, but significant pressure drop is only formed once the exhaust is nearly blocked
Solution Approach 1:
The radiation receiver system provides early warning of deposit formation by continuously monitoring radiation transmission through the exhaust pipe. Even thin layers of deposits attenuate radiation, allowing detection well before pressure drop becomes significant. This enables preventive maintenance or operational adjustments before the exhaust approaches blockage conditions.
4Ease of operation
If visual inspection is used to detect deposits, then deposit detection is achieved, but it requires manual intervention and cannot continuously monitor deposits
Solution Approach 1:
The radiation receiver system automatically and continuously monitors the exhaust pipe for deposit formation without requiring manual intervention. The receivers are positioned to continuously measure radiation transmission, and the system self-regulates by providing real-time deposit information to control systems, enabling automated response to deposit conditions.
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
Enables automatic and accurate detection and removal of urea deposits, preventing blockages and maintaining SCR system performance by adjusting urea flow and temperature.
Implementation Method 1
at least one radiation receiver which, in use, is located within the exhaust pipe downstream of the nozzle... the receiver is adapted to communicate radiation data to the control unit
Data Source
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AI summary
An apparatus for detecting urea deposits in an exhaust pipe (12) of an internal combustion engine (10) is provided, where the urea is introduced into the exhaust pipe (12) in an aqueous urea solution via a nozzle (18). The apparatus comprises at least one radiation receiver (16) which, in use, is located within the exhaust pipe (12) downstream of the nozzle (18). The apparatus further comprises an electronic control unit (30) in communication with the receiver (16), wherein the receiver (16) communicates radiation data to the control unit which allows the control unit to establish whether deposits have formed within the exhaust pipe (12). A control valve (22) is also provided which controls flow of the solution to the nozzle (18) in response to signals from the control unit (30). A method of detecting urea deposits in an exhaust pipe of an internal combustion engine is also provided, as is an automotive vehicle incorporating the aforementioned apparatus.