Temperature Sensor Getter Adsorption for Aggressive Gas Protection
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Solution Overview
Problem
Measuring devices in hostile environments, such as reactors, face contamination and corrosion due to aggressive gases penetrating protective layers, leading to frequent thermocouple failures, especially at high temperatures where ceramics can become porous, and existing purging methods only provide limited protection.
Innovation Solution
A sensing assembly featuring a protective tube with an intermediate chamber that can be purged with a gas and incorporates an adsorbing unit made of getter materials to absorb reactive gases, combined with a gas conduit system for continuous gas flow and pressure regulation, allowing for extended sensor lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers of protective materials (metals and ceramics) are used to protect sensitive parts, then protection against aggressive gases is improved, but at high temperatures ceramics become porous allowing gas penetration
Solution Approach 1:
The patent introduces a vacuum environment in the annular space between the protective layers and the sensitive parts, replacing the aggressive process atmosphere with a vacuum (inert environment). This prevents aggressive gases from reaching the sensitive parts through the protective layers, solving the problem of gas penetration through porous ceramics at high temperatures.
2Reliability
If a vacuum environment is created in the annular space, then protection against aggressive gases is significantly improved, but the system complexity increases due to additional vacuum components
Solution Approach 1:
The system automatically maintains the vacuum environment through a control unit that monitors pressure sensors and activates vacuum generators only when needed (when pressure exceeds threshold values). This self-regulating mechanism reduces the need for continuous complex vacuum system operation, allowing the system to maintain protection while minimizing active vacuum components.
3Reliability
If continuous purging gas flow is used to protect the sensor, then corrosion is reduced, but the protection is only effective for limited time (approximately one month)
Solution Approach 1:
The patent creates a vacuum environment instead of using continuous purging gas flow. This vacuum barrier provides long-term protection against aggressive gases without the limitations of purging gas effectiveness, extending the sensor lifespan beyond the one-month limitation of purging methods.
Solution Approach 2:
The patent replaces the mechanical purging gas flow system with a vacuum-based protection system. This substitution provides more effective and longer-lasting corrosion protection, as the vacuum creates a physical barrier that prevents aggressive gases from reaching the sensor, unlike purging gas which only reduces oxidation and contamination temporarily.
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 combination of purging gas and getter materials significantly increases the lifespan of sensing assemblies by maintaining gas purity and preventing corrosion, with the adsorbing unit remaining effective for several months and requiring efficient reactivation through heating, thus extending the operational life beyond what is achievable with purging alone.
Implementation Method 1
incorporates an adsorbing unit made of getter materials to absorb reactive gases
Implementation Method 2
at least the intermediate chamber can be purged by means of a purging gas via the gas conduit means
Implementation Method 3
requiring efficient reactivation through heating
Data Source
Figure 1~1b
Figure 2~2b
Figure 3~3b
AI summary
The present invention refers to a sensing assembly (1), preferably for sensing a temperature, and a method for fabricating such sensing assembly (1), , which sensing assembly (1) comprises at least - one measuring insert (6), preferably for sensing a temperature, - one, preferably pre-formed, fitting (10a-10c) at least partially surrounding the measuring insert (6), - one protective tube (11), wherein the measuring insert (6) and the pre-formed fitting (10a-10c) are positioned within an inner cavity of the protective tube (11) such, that an intermediate chamber (12) is formed, and - gas conduit means (3) including at least a gas-inlet (4) and a gas-outlet (5) both at least connected to the intermediate chamber (12). According to the present invention, the sensing assembly (1) further comprises at least one adsorbing unit (14), which is at least partially comprised of a getter material, and at least partially positioned inside the protective tube (11).