Gas Measuring Cell with Vacuum Window Inserts for High Temperature Calibration
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Solution Overview
Problem
Existing gas measuring cells face challenges in the high-temperature range due to limitations of flexible sealing materials, which fail at temperatures above 800 °C, and traditional heat-resistant materials like platinum can act as catalysts, leading to leaks and inaccurate measurements.
Innovation Solution
A gas measuring cell design featuring a hollow body with a heated central zone and unheated transition zones, using evacuated window inserts to maintain a sealed environment without the need for high-temperature sealing materials, allowing for temperatures up to 1400 °C and ensuring constant gas temperature within the optically effective measuring zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible sealing materials are used in gas measuring cells, then ease of manufacture and sealing reliability are improved at low temperatures, but the device fails at high temperatures above 800 °C
Solution Approach 1:
The gas measuring cell is divided into a hot zone (analysis chamber) and a cold zone (window mounting area) separated by a thermal barrier. This segmentation allows different temperature conditions in different regions, enabling the use of vacuum-sealed windows in the cold zone while maintaining high temperature in the analysis chamber for calibration.
Solution Approach 2:
A thermal barrier acts as an intermediary element between the heated analysis chamber and the window mounting area. This barrier prevents heat transfer to the windows and their seals, allowing the use of standard sealing materials in the window area while maintaining high temperatures in the measurement zone.
2Strength
If platinum layer is used as intermediate material for diffusion bonding, then connection strength is improved, but catalytic activity causes measurement errors
Solution Approach 1:
The platinum catalytic layer is completely removed from the gas measuring cell design. Instead of using diffusion bonding with platinum intermediate material, the invention employs vacuum sealing of windows to the flange, eliminating the source of catalytic interference while maintaining structural integrity through alternative sealing mechanisms.
3Device complexity
If windows are sealed directly to the heated base body, then device complexity is reduced, but sealing reliability fails due to thermal expansion differences
Solution Approach 1:
The sealing structure is segmented into a cold flange region for window mounting and a hot analysis chamber region. The thermal barrier creates distinct thermal zones, allowing windows to be sealed to the cold flange where standard sealing materials remain effective, while the analysis chamber maintains high temperature for calibration purposes.
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 reliable calibration of optical gas analyzers and optical analysis of high-temperature processes without the issues of heat-resistant sealing material failures, maintaining a gas-tight and accurate measurement environment across a wide temperature range.
Implementation Method 1
The window insert extends through the unheated transition zone into the heated middle zone in the hollow body, with at least the first window facing the heated middle zone being held in the window insert by a vacuum present in the intermediate space.
Data Source
Figure 1
Figure 2
AI summary
The gas measuring cell (1) has a hollow body, where a sample, which is to be analyzed, is placed over a gas inlet (10) and a gas outlet (11). An analyzing chamber is placed in the central zone (14). An unheated transition zone is connected to the analyzing chamber at both sides. The window slots (8,9) are provided. The window slot is mounted at the front sides (6,7) of the base body and projects into the hollow body. The window slot has two windows (17,18) spaced in longitudinal axis and permeable for the measuring radiation.