Drop-in Sensor Immersion and Cable Protection
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Solution Overview
Problem
Conventional drop-in sensors for measuring molten metal temperatures and carbon content face challenges such as buoyancy issues due to slag density variations, incomplete immersion, and signal cable damage during the steelmaking process, particularly during the 'in-blow' phase, leading to inaccurate and unreliable measurements.
Innovation Solution
A drop-in sensor with a forward-facing bath thermocouple and a thermally isolated solidification chamber, designed to maximize the overall measuring head density and minimize buoyant tendencies, ensuring consistent immersion and protecting the signal cable with a strategically positioned extension tube, allowing for accurate bath and liquidus temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drop-in sensor is designed with conventional density, then it can be easily manufactured and deployed, but it floats on the molten metal surface due to buoyancy forces from slag layer, preventing proper immersion and measurement
Solution Approach 1:
The patent applies the anti-weight principle by incorporating high-density materials (such as tungsten or depleted uranium) into the sensor housing to counteract the buoyant force exerted by the molten metal and slag layer. This counterweight mechanism ensures the sensor sinks to the required depth for accurate measurement without floating on the surface, directly resolving the contradiction between measurement reliability and structural simplicity.
2Measurement precision
If the thermocouple is positioned to face the immersion direction, then it can accurately measure bath temperature during in-blow conditions, but the signal cable becomes vulnerable to damage from molten metal and slag contact
Solution Approach 1:
The patent employs an intermediary protective structure (such as a ceramic boot or refractory material shielding) that surrounds the signal cable and thermocouple assembly. This intermediary barrier protects the sensitive electrical components from direct contact with molten metal and slag, preventing cable damage while allowing the thermocouple to maintain its forward-facing orientation for accurate temperature measurement during in-blow conditions.
Solution Approach 2:
The patent positions the thermocouple to face the immersion direction (forward-facing orientation) while routing the signal cable through a protected pathway along the sensor body. This dimensional separation allows the measurement element to be optimally oriented for accuracy while the cable is positioned in a protected dimension, away from direct exposure to harmful molten materials.
3Speed
If the solidification chamber is thermally connected to the molten metal bath, then it can rapidly cool the sampled metal, but it acts as a heat pump heating the liquid phase and causing liquidus measurement errors
Solution Approach 1:
The patent extracts the solidification chamber from thermal connection with the molten metal bath by introducing thermal insulation barriers (such as ceramic or refractory material layers) between the chamber and the surrounding bath environment. This extraction of thermal connection allows the chamber to rapidly cool the sampled metal for speed while preventing the chamber from acting as a heat pump that would heat the liquid phase and cause measurement errors, thus resolving the contradiction between cooling speed and measurement precision.
4Measurement precision
If auxiliary lances are installed to immerse multifunctional sensor probes, then temperature and carbon content measurements can be obtained, but large capital expense and ongoing maintenance costs are required
Solution Approach 1:
The patent employs a disposable drop-in sensor design that can be easily manufactured and deployed without requiring expensive auxiliary lances or complex installation infrastructure. The sensor is designed for single-use or limited-use applications, eliminating the need for costly capital investment in permanent lance systems and reducing ongoing maintenance expenses, while still providing accurate temperature and carbon content measurements through optimized sensor geometry and material selection.
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 solution enables cost-effective, reliable, and rapid temperature and carbon content measurements during the steelmaking process, even under challenging 'in-blow' conditions, by ensuring proper immersion and protecting the signal cable from damage, thus improving measurement accuracy and reducing operational costs.
Implementation Method 1
a forward facing bath thermocouple
Implementation Method 2
a reverse-filling solidification chamber
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
A drop-in probe includes a measurement head having an immersion end and an opposing second end having an end face. The measurement head is formed of first and second body halves configured to mate together along a parting line. A sample chamber, arranged within the measurement head, is thermally isolated from a cooling mass thereof and includes a metal wall having a thickness of 2.5 mm or less. An inlet tube has an inlet opening to the sample chamber. The inlet opening has a diameter Diniet and is spaced apart from the end face of the measurement head at a distance of at least formula (1). When the sample chamber is filled with a sample of the molten metal, a ratio of a mass of the metal sample to a mass of the metal wall of the sample chamber is greater than 2.6 and less than 6.