Metering Arrangement Separate Heating Sequences
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Solution Overview
Problem
Existing metering systems for exhaust gas treatment face damage due to the freezing of aqueous urea solutions, which expand in volume upon thawing, causing mechanical stress on components.
Innovation Solution
A metering arrangement with separate heating devices for different components, allowing for controlled thawing and freezing sequences to manage the volume expansion of the reducing agent solution, ensuring sensitive components are protected by thawing or freezing them last or first, depending on their sensitivity and the operational needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reducing agent solution is frozen to protect sensitive components, then damage to components is prevented, but the volume expansion during freezing causes mechanical stress on components
Solution Approach 1:
The metering arrangement is divided into multiple components (supply container, pump, metering device, pipelines) each with separate heating devices. This segmentation allows selective and sequential freezing/thawing of individual components, enabling the system to manage volume expansion stresses locally rather than globally, thus protecting sensitive components while controlling mechanical stress.
Solution Approach 2:
The system performs preliminary heating of components before freezing occurs, and preliminary thawing of components before they are subjected to operational stress. By controlling the sequence of heating and thawing operations in advance, the system prepares components to accommodate volume expansion without suffering damage, thus preventing component damage while managing mechanical stress.
2Productivity
If heating devices operate simultaneously to thaw all components, then thawing efficiency is improved, but volume expansion forces cause damage to components
Solution Approach 1:
The heating devices operate in periodic sequences rather than simultaneously. The control device activates heating devices in a predetermined sequence, with each component being heated and thawed at different times. This periodic action allows volume expansion to occur gradually as each component thaws in sequence, preventing damaging force buildup while maintaining overall system productivity through coordinated cyclic heating operations.
Solution Approach 2:
Components are heated and thawed in a predetermined sequence before they are subjected to operational use. The supply container is thawed first, followed by the pump, then the metering device and pipelines. This preliminary sequential thawing ensures that each component is ready to accommodate the reducing agent solution without suffering damage from sudden volume expansion, thus protecting component integrity while maintaining system productivity.
3Reliability
If multiple heating devices are used to control freezing sequences, then component protection is improved, but device complexity increases
Solution Approach 1:
The heating devices serve multiple functions: they can heat individual components selectively, operate in sequence to control freezing/thawing patterns, and work cooperatively to protect different components based on their sensitivity. The control device manages multiple heating devices with a single control logic that adapts to the specific needs of each component, thus achieving comprehensive component protection without proportionally increasing system complexity.
Solution Approach 2:
The system controls the operational parameters (timing, duration, intensity) of each heating device to optimize component protection. By adjusting the heating parameters dynamically based on component sensitivity and environmental conditions, the system achieves effective protection against freezing damage without requiring overly complex heating infrastructure, thus maintaining reliability while managing device complexity.
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 effectively prevents damage from volume expansion during freezing and thawing by sequencing the heating of components, allowing sensitive parts to absorb volume increases safely, thus extending the lifespan of the metering system components while maintaining operational efficiency.
Implementation Method 1
at least one heating device (18, 28, 30, 38, 40, 42) for heating at least one component (14, 24, 26, 32, 34, 36) of the metering arrangement (10)
Implementation Method 2
the volume of the frozen solution increases when is heated from a temperature below the freezing point up to the freezing point
Implementation Method 3
The freezing point of a commercial aqueous urea solution lies below that of water, and it can freeze at very low outside temperatures of less than −11° C
Data Source
AI summary
A method and arrangement for controlling heating and thawing of a metering arrangement with a metering device for the feeding of a reducing agent solution for the exhaust gas after treatment in an exhaust system. The metering device is connected with a supply container for the reducing agent solution via at least one pipe. At least one heating device is provided for the heating of at least one component of the metering arrangement. At least one first component of the metering arrangement is assigned a first heating device, which can be operated separately from a second heating device provided for the heating of at least a second component of the metering arrangement.