Exhaust Gas Probe Segmentation for Steel Furnace Sampling
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Solution Overview
Problem
Existing probes for continuous analysis of waste gas in metal melting vessels, such as electric arc furnaces, face challenges in measurement accuracy due to temperature and contamination susceptibility, and air infiltration through gaps, leading to falsified results.
Innovation Solution
A robust probe design with a cylindrical body, limited water cooling to prevent condensation, and a backflush system for cleaning, flanged to the vessel cover with a pivoting elbow, allowing for continuous and accurate exhaust gas sampling and analysis using a mass spectrometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the probe extends far into the exhaust gas stream, then the measuring surface is relatively small, but the probe is more susceptible to temperature and contamination disturbances
Solution Approach 1:
The probe is segmented into distinct functional zones: a measurement section with the opening flush to the wall for accurate sampling, and a separate cooling section below the measurement point. This segmentation allows the measurement area to remain hot for accurate exhaust gas analysis while the cooling section prevents condensation without interfering with measurements.
Solution Approach 2:
A coolant supply line and cooling system act as an intermediary element, introducing cooling medium below the measurement point to prevent condensation of water vapor in the exhaust gas, thereby protecting the measurement system from harmful condensation effects without directly cooling the measurement zone.
2Reliability
If the probe cooling system is extended along the entire probe length, then condensation is prevented, but water vapor in the exhaust gas condenses below the dew point affecting measurement accuracy
Solution Approach 1:
The cooling system is applied locally only to the lower section of the probe below the measurement point, rather than uniformly along the entire probe length. This local cooling approach prevents condensation in the measurement-free zone while maintaining accurate temperature conditions for exhaust gas measurement at the probe opening.
3Ease of manufacture
If a flanged connection is used between the manifold and flap piece, then assembly is simplified, but false air is drawn in through the gap distorting analysis results
Solution Approach 1:
The probe opening is extracted from the conventional flanged connection gap area and positioned flush with the inner wall of the sampling point. This extraction removes the measurement function from the problematic gap region where false air infiltration occurs, thereby eliminating the source of measurement distortion while maintaining the simple flanged assembly structure.
4Measurement precision
If the probe opening is flush with the furnace wall, then false air infiltration is reduced, but the measuring surface area is limited
Solution Approach 1:
The probe design transitions from a two-dimensional wall-mounted opening to a three-dimensional cylindrical body extending into the exhaust gas stream. This dimensional change allows the probe opening to remain flush with the wall for accurate sampling while the cylindrical structure provides additional surface area for gas interaction and sampling efficiency.
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 probe enables high-accuracy, continuous analysis of exhaust gases, including water vapor and rare components, with improved robustness and reliability, ensuring optimal measurement conditions and effective cleaning, thereby enhancing process transparency and operational efficiency.
Implementation Method 1
the gas to be analyzed, cooled from a maximum of 1800°C, is not cooled below the dew point in the area above the cooling, so that the water vapor present in the exhaust gas cannot condense
Implementation Method 2
a pressure is possible that can be significantly higher than 6 bar, for example 13 bar
Data Source
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AI summary
The invention relates to a probe for continuously measuring exhaust gases on vessels for melting metals, in particular on electric furnaces for producing steel, which probe is characterized by a cylindrical body which can be attached by an open end to the removal point by means of a flange, while the opposite end can be closed off and just below the end which can be closed off at least one connector element for the line leading to an analysis device and a probe cooling means is provided, having a coolant-feed line and coolant-discharge line.