Determining a location and size of a gas source with a spectrometer gas monitor
Inventors
Prasad, Kuldeep • ALDEN, CAROLINE • Rieker, Gregory Brian • Wright, Robert James • COBURN, SEAN
Assignees
University of Colorado Denver • United States Department of Commerce
Publication Number
US-10240998-B2
Publication Date
2019-03-26
Expiration Date
2036-05-11
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Abstract
A process for determining a location and size of a gas source within an area with a spectrometer gas monitor includes: providing the spectrometer gas monitor; performing fence line monitoring of the area with the spectrometer gas monitor; collecting spectroscopic data over multiple open paths around the area with the spectrometer gas monitor; measuring atmospheric conditions along gas inflows and gas outflows of the area; subtracting a background for a selected gas from the spectroscopic data; applying a boundary constraint to the spectroscopic data; determining an atmospheric concentration of air entering the area; applying bootstrapping to the spectroscopic data; applying zero minimum elimination to the spectroscopic data; and producing inversion data from the spectroscopic data to determine the location and size of the gas source within the area.
Core Innovation
The invention provides a process and system for determining a location and size of a gas source within an area using a spectrometer gas monitor. The process involves performing fence line monitoring of the area, collecting spectroscopic data over multiple open paths around the area, measuring atmospheric conditions along gas inflows and outflows, subtracting background concentrations of a selected gas from the spectroscopic data, applying boundary constraints, determining atmospheric concentrations of incoming air, applying bootstrapping and zero minimum elimination techniques, and producing inversion data to precisely locate and size the gas source within the area.
The spectrometer gas monitor uses frequency comb lasers that produce hundreds or thousands of individual wavelengths, allowing accurate, drift-free, and calibration-free measurements of gases such as methane and its isotopes, water vapor, and other species. The system includes a light source projecting source light over multiple open paths and retroreflectors that reflect the light back to detectors in the spectrometer to collect continuous spectroscopic measurements. Orthogonal beam sampling and clustering of multiple spectrometer monitors can be utilized to enhance measurement accuracy and coverage over large areas.
The problem being addressed is the need for reliable, continuous, and accurate monitoring of gas leaks, especially methane leaks, from natural gas facilities over large areas, often exceeding 1 square kilometer. Traditional single point or sparse wavelength absorption and LIDAR approaches have limitations in providing accurate, drift-free, and operator-independent measurements for multiple simultaneous gas sources. This invention solves these issues by providing a robust, sensitive, and statistically certain monitoring system capable of locating and sizing small gas leaks with continuous and wide-area coverage.
Claims Coverage
The patent includes five independent claims covering a process, a computer-implemented method, a system, and a computer-readable medium related to determining the location and size of a gas source using a spectrometer gas monitor.
Process for determining gas source location and size using spectrometer gas monitor
A sequence of steps comprising fence line monitoring with a spectrometer gas monitor, collecting spectroscopic data over multiple open paths, measuring atmospheric conditions along gas inflows and outflows, subtracting a background gas concentration, applying boundary constraints, determining atmospheric concentration of incoming air, applying bootstrapping and zero minimum elimination techniques, and producing inversion data to determine the gas source's location and size within the area.
Arranging plurality of spectrometer gas monitors by clustering
When the monitored area is larger than 1 km2, arranging multiple spectrometer gas monitors into clusters to optimize coverage and performance.
Performing orthogonal beam sampling
Using pairs of retroreflectors positioned such that the gas source is interposed between them to constrain atmospheric conditions upwind and downwind of the area.
Spectrometer gas monitor comprising a light source, retroreflectors, and detector
The monitor includes a light source emitting source light as multiple open-path beams, retroreflectors that reflect this light back as reflected light, and a detector receiving the reflected light to obtain spectroscopic data.
Using a source frequency comb and reflected frequency comb for absorption measurement
Source light includes a source frequency comb with comb teeth of a first intensity, and reflected light includes the reflected frequency comb with comb teeth of a second intensity; the difference in intensity arises from absorption by the gas.
These inventive features cover an integrated approach to detect, locate, and size gas leaks by combining advanced spectroscopic measurements with atmospheric modeling and statistical analysis, including deployment strategies for coverage optimization and improved data reliability.
Stated Advantages
Provides determination of the location and size of gas leaks within an area with statistical certainty.
Enables temporally continuous monitoring of gases over ranges from tens to thousands of meters.
Offers calibration-free and drift-free measurements using frequency comb spectroscopy.
Accurately measures multiple gas species and isotopes simultaneously, allowing differentiation of biogenic or thermogenic sources.
Reduces false positive leak identifications by employing bootstrapping and zero minimum elimination methods.
Requires no operator involvement and can integrate multiple point sources simultaneously.
Flexible retroreflector placement enables monitoring under various weather conditions and topographies.
Documented Applications
Continuous monitoring and quantification of methane leaks at natural gas production facilities covering areas larger than 1 km2.
Detecting and sizing small methane leaks from oil and natural gas well pads in field environments using open-path laser spectroscopy.
Quasi-continuous atmospheric observing systems for leak detection and source attribution in large natural gas fields.
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