Gas Filter Correlation Radiometer Ethane Leak Detection
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Solution Overview
Problem
Existing remote sensing techniques face challenges in detecting natural gas leaks due to high background concentrations of methane (CH4) in the atmosphere, leading to false signatures and reduced detectivity, especially when detecting leaks from underground pipes where thermal noise is significant.
Innovation Solution
Utilizing ethane (C2H6) as a target gas, which has a much lower atmospheric concentration and strong absorption/emission bands at 3000 cm−1, allowing for improved detection with a gas filter correlation radiometer (GFCR) that reduces thermal noise and enhances radiative contrast, enabling the detection of natural gas pipeline leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If methane (CH4) is used as the target gas for detection, then the detection target is readily available as it comprises 95% of natural gas, but the high atmospheric background concentration (1.7 ppm) leads to false signatures and reduced measurement precision
Solution Approach 1:
The patent extracts ethane (C2H6) as a specific detection target from natural gas, separating it from the dominant methane component. Although ethane comprises only 5-20% of natural gas, its extremely low atmospheric background concentration (860 ppt vs 1.7 ppm for methane) makes it a superior tracer for leak detection, eliminating false positives from background variability
Solution Approach 2:
The patent changes the detection parameter from methane concentration to ethane concentration. By targeting ethane's specific absorption features at 3000 cm−1 rather than methane's features, the system achieves higher measurement precision because ethane's atmospheric background is 2000 times smaller and more stable, reducing false signatures from environmental variability
2Measurement precision
If the long wavelength infrared region (7.8 μm) is used for CH4 detection, then the upwelling radiation is primarily from the earth's surface minimizing background CH4, but the radiative contrast between surface and leaked methane is very small reducing detectivity
Solution Approach 1:
The patent changes the detection wavelength from 7.8 μm (methane's absorption band) to 3.33 μm (ethane's absorption band at 3000 cm−1). This parameter change simultaneously achieves both goals: the shorter wavelength provides stronger radiative contrast between surface and leaked gas while ethane's low atmospheric concentration ensures minimal background interference, resolving the contradiction between background reduction and leak detectivity
3Reliability
If a shorter wavelength absorption band of CH4 is used, then the radiative contrast between source and leaked gas is greatly increased and thermal noise is reduced, but the background of CH4 becomes very large as solar radiation passes through the entire atmosphere
Solution Approach 1:
The patent extracts ethane as the detection target and uses its specific absorption band at 3000 cm−1. This extraction resolves the contradiction because ethane's atmospheric concentration is so low (860 ppt) that even when measuring through the entire atmospheric path at the shorter 3.33 μm wavelength, the background signal remains negligible compared to the strong radiative contrast provided by leaked ethane plumes
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 method effectively detects natural gas leaks by minimizing background interference and reducing thermal noise, providing a higher signal-to-noise ratio and improved sensitivity to ethane, enabling the detection of smaller leaks with increased accuracy and precision.
Implementation Method 1
C2H6 has a strong absorption/emission band(s) at 3000 cm−1 (3.33 μm). In this spectral region, the upwelling radiation will consist primarily of reflected solar radiation.
Implementation Method 2
measuring absorption of upwelling electromagnetic radiation that has passed through natural gas
Data Source
AI summary
A gas filter correlation radiometer mounted on an aircraft is flown over a target area. The gas filter correlation radiometer is configured to detect ethane (C2H6) gas in the event of a gas leak. The gas filter correlation radiometer uses background radiation to detect ethane.