Multispectral SWIR Gas Imaging Sensor for Leak Quantification
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Solution Overview
Problem
Current gas imaging technologies face limitations in detecting and quantifying hydrocarbon gas leaks, particularly methane, due to reliance on thermal contrast, poor performance in humid conditions, and inability to estimate leak rates, especially in scenarios where thermal infrared sensors fail to provide reliable results.
Innovation Solution
The use of multispectral short-wave infrared (SWIR) imaging with differential absorption spectroscopy, employing multiple spectral filters and detectors sensitive to 1.0-2.6 microns, allows for rapid detection, localization, and quantification of hydrocarbon gas leaks using natural or artificial illumination, independent of thermal contrast and resistant to water vapor interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal infrared sensors are used for gas detection, then detection capability is improved, but performance deteriorates in humid conditions and when thermal contrast is absent
Solution Approach 1:
The patent changes the detection parameter from thermal infrared wavelength to short-wave infrared wavelength (1.0-2.6 microns). This parameter change allows the system to detect hydrocarbon gases through differential absorption spectroscopy without relying on thermal contrast, thereby eliminating the harmful effect of water vapor interference while maintaining reliable detection capability
Solution Approach 2:
The patent introduces multiple spectral filters as intermediaries to selectively transmit specific wavelength bands through the gas plume. These filters enable differential absorption measurements at multiple wavelengths, allowing the system to distinguish hydrocarbon gas absorption from water vapor absorption and achieve reliable detection in humid conditions
2Reliability
If thermal infrared imaging is used for gas detection, then leak detection is improved, but ability to quantify leak rate deteriorates
Solution Approach 1:
The patent segments the spectral information into multiple wavelength bands using spectral filters. By analyzing absorption characteristics across different wavelength segments, the system can determine both the presence of gas (detection) and the column density (quantification). This segmented spectral analysis enables estimation of leak rates by measuring the amount of gas in the plume
Solution Approach 2:
The patent transitions from single-wavelength thermal infrared detection to multi-wavelength short-wave infrared spectroscopy. This adds the spectral dimension to the spatial imaging, enabling the system to extract quantitative information about gas concentration and column density from the absorption characteristics at multiple wavelengths, thereby achieving leak rate estimation
3Reliability
If mid-wave or long-wave infrared sensors are used, then gas detection is improved, but cost and complexity increase due to cryogenic cooling requirements
Solution Approach 1:
The patent changes the operating wavelength from mid-wave or long-wave infrared to short-wave infrared (1.0-2.6 microns). This parameter change enables the use of simpler detectors that do not require cryogenic cooling, as short-wave infrared detectors can operate at higher temperatures while still providing reliable gas detection through differential absorption spectroscopy
Solution Approach 2:
The patent replaces expensive cryogenically-cooled infrared sensors with more affordable short-wave infrared detectors. While the detectors have shorter operational lifetimes without cryogenic cooling, the elimination of complex cooling systems makes the overall system more cost-effective and suitable for widespread deployment in gas safety and emissions monitoring applications
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
Enables accurate and cost-effective detection and quantification of hydrocarbon gas leaks from various sources, including underground and surface emissions, with the ability to estimate leak rates and mass flux, even in humid conditions, providing rapid response times and flexible scan patterns for safety and emissions monitoring.
Implementation Method 1
The sensor system utilizes a short-wave infrared radiation detector in combination with multiple spectral filters to scan a site and detect hydrocarbon gas leaks by measuring light absorption at select wavelengths characteristic of the molecular composition of the gas
Implementation Method 2
differential absorption gas imaging in the short-wave infrared part of the spectrum...exploiting the absorption of light (typically in different parts of the infrared spectrum) at select wavelengths characteristic of the molecular composition of the gas of interest
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Apparatus and methods for rapidly detecting, localizing, imaging, and quantifying leaks of natural gas and other hydrocarbon and greenhouse gases. Scanning sensors, scan patterns, and data processing algorithms enable monitoring a site to rapidly detect, localize, image, and quantify amounts and rates of hydrocarbon leaks. Multispectral short-wave infrared detectors sense non-thermal infrared radiation from natural solar or artificial illumination sources by differential absorption spectroscopy. A multispectral sensor is scanned to envelop an area of interest, detect the presence and location of a leak, and raster scan the area around the leak to create an image of the leak. The resulting absorption image related to differential spectral optical depth is color mapped to render the degree of gas absorption across the scene. Analysis of this optical depth image, with factors including known inline pressures and/or surface wind speed measurements, enable estimation of the leak rate, i.e., emission mass flux of gas.