Optical Fiber Sensor Sheath for Molten Metal Temperature Measurement
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Solution Overview
Problem
Optical fibers used for temperature measurement in molten metals face rapid degradation due to high temperatures, requiring frequent replacement and inefficient measurement processes.
Innovation Solution
A device with a metal tube sheath and an intermediate layer made of powder or fibrous material surrounds the optical fiber, allowing for controlled thermal expansion and sudden release, facilitating quick exposure to molten metals and maintaining fiber integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical fiber is directly immersed in molten metal for temperature measurement, then the measurement function is achieved, but the fiber degrades rapidly due to high temperature
Solution Approach 1:
The protective structure is divided into multiple layers: an outer metal tube layer for mechanical protection and thermal management, and an inner powder/fibrous material layer for thermal insulation. This segmentation allows each layer to perform its specific function, protecting the optical fiber from direct exposure to molten metal while enabling temperature measurement through controlled thermal coupling.
Solution Approach 2:
The powder or fibrous material layer acts as an intermediary between the optical fiber and the molten metal environment. This intermediate layer provides thermal insulation during normal operation, keeping the fiber cool, while allowing thermal energy transfer when needed for measurement, thus mediating between the fiber's need for low temperature and the measurement requirement for high temperature exposure.
2Strength
If the optical fiber is surrounded by a simple protective tube, then mechanical protection is provided, but thermal insulation is insufficient and fiber still degrades
Solution Approach 1:
The protective structure uses composite materials combining a metal tube (for mechanical strength and structural integrity) with a powder or fibrous material (for thermal insulation). This composite construction provides both mechanical protection and effective thermal insulation, preventing the optical fiber from overheating while maintaining structural robustness in the harsh molten metal environment.
3Productivity
If the optical fiber is continuously exposed to molten metal for measurement, then temperature data is obtained, but the fiber tip is destroyed and requires frequent replacement
Solution Approach 1:
The powder or fibrous material layer serves as a pre-prepared thermal buffer that absorbs and mitigates the extreme heat from the molten metal before it reaches the optical fiber. This beforehand cushioning effect allows the fiber to withstand prolonged exposure to the harsh environment without degradation, ensuring continuous reliable measurement without frequent replacements.
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
The device enables prolonged and accurate temperature measurement by maintaining the optical fiber at a low temperature until sudden heating, allowing for rapid equilibration with the molten metal temperature, thus extending fiber lifespan and improving measurement precision.
Implementation Method 1
the light-conducting element of which is usually quartz glass
Implementation Method 2
The radiation picked up by the optical fiber is evaluated by a detector
Data Source
Figure 1
Figure 2~3
Figure 4a~4c
AI summary
The invention relates to a method for measuring a characteristic parameter, in particular a temperature, of a melt, in particular a metal melt, by means of an optical fiber surrounded by a sheath, wherein the optical fiber is immersed in the melt and wherein the radiation absorbed by the optical fiber in the melt is supplied to a detector, wherein the optical fiber is heated when immersed in the melt and consists in the fact that the heating curve of the optical fiber has at least one point P(t0,T0), wherein the rise ΔT1 of the temperature T of the optical fiber over the time Δt in a first time interval t0-Δt up to the temperature T0 is smaller than the rise ΔT2 of the temperature of the optical fiber over the time Δt in an immediately following second time interval t0+Δt.