Volume flow calculations on gas leaks imaged with infrared gas-correlation

Sandsten, Jonas; Andersson, Martin

doi:10.1364/oe.20.020318

Cited by 20 publications

(13 citation statements)

References 13 publications

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“…One newly developed technique that allows for quantification and localization is ground-based remote sensing via gas imaging cameras [21][22][23]. Gas imaging includes capturing video images of methane plumes in the environment to quantify emission rates.…”

Section: Introductionmentioning

confidence: 99%

“…This technique shows promise as it offers high spatiotemporal resolution in mapping gas concentrations as well as possibility of automation and continuous monitoring of sites. In addition, ancillary equipment for wind measurement is not required, since with high frequency imaging (e.g., >1 Hz) gas velocities inside the plume can be approximated by tracking plume features in consecutive images using velocimetry algorithms such as minimum quadratic differences [25], cross-correlation between consecutive images [26], and block-matching [21]. With the measured methane concentration and the estimated flow velocity, the emission rates can be computed based on the principle of mass balance.…”

Section: Introductionmentioning

confidence: 99%

“…For example, increased spatial and temporal resolution of imaging cameras translate into lower uncertainty in concentration measurement and velocity estimation which in turn leads to lower total uncertainty in leak quantification [27]. Instrumentation uncertainties are usually reported by manufacturers and have been previously studied in detail [21,22,26,28]. Meanwhile, the transformation of concentrations and velocities into emission rates is also an uncertain process.…”

Section: Introductionmentioning

confidence: 99%

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On the Viability of Video Imaging in Leak Rate Quantification: A Theoretical Error Analysis

Montazeri

Zhou

Albertson

2021

Sensors

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Optical gas imaging through multispectral cameras is a promising technique for mitigation of methane emissions through localization and quantification of emissions sources. While more advanced cameras developed in recent years have led to lower uncertainties in measuring gas concentrations, a systematic analysis of the uncertainties associated with leak rate estimation have been overlooked. We present a systematic categorization of the involved uncertainties with a focus on a theoretical analysis of projection uncertainties that are inherent to this technique. The projection uncertainties are then quantified using Large Eddy Simulation experiments of a point source release into the atmosphere. Our results show that while projection uncertainties are typically about 5% of the emission rate, low acquisition times and observation of the gas plume at small distances from the emission source (<10 m) can amount to errors of about 20%. Further, we found that acquisition times on the order of tens of seconds are sufficient to significantly reduce (>50%) the projection uncertainties. These findings suggest robust procedures on how to reduce projection uncertainties, however, a balance between other sources of uncertainty due to operational conditions and the employed instrumentation are required to outline more practical guidelines.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Viability of Video Imaging in Leak Rate Quantification: A Theoretical Error Analysis

Montazeri

Zhou

Albertson

2021

Sensors

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“…The optical flow method is another motion-estimation technique. It has been validated using suspended objects (e.g., leaking gases [23] or sulfur dioxide flux) from infrared images or CCD images and has already been suggested as a promising method for detection of gas leaks moving patterns by von Deimling et al [18]. In this paper, two types of information, amplitude and velocity, are comprehensively considered, and an automatic detection method for underwater gas leaks is designed to distinguish other strong scatterers in the water such as the seafloor.…”

Section: Introductionmentioning

confidence: 99%

Optical Flow-Based Detection of Gas Leaks from Pipelines Using Multibeam Water Column Images

Zhou

et al. 2020

Remote Sensing

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In recent years, most multibeam echo sounders (MBESs) have been able to collect water column image (WCI) data while performing seabed topography measurements, providing effective data sources for gas-leakage detection. However, there can be systematic (e.g., sidelobe interference) or natural disturbances in the images, which may introduce challenges for automatic detection of gas leaks. In this paper, we design two data-processing schemes to estimate motion velocities based on the Farneback optical flow principle according to types of WCIs, including time-angle and depth-across track images. Moreover, by combining the estimated motion velocities with the amplitudes of the image pixels, several decision thresholds are used to eliminate interferences, such as the seabed, non-gas backscatters in the water column, etc. To verify the effectiveness of the proposed method, we simulated the scenarios of pipeline leakage in a pool and the Songhua Lake, Jilin Province, China, and used a HT300 PA MBES (it was developed by Harbin Engineering University and its operating frequency is 300 kHz) to collect acoustic data in static and dynamic conditions. The results show that the proposed method can automatically detect underwater leaking gases, and both data-processing schemes have similar detection performance.

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“…In recent years, researchers have explored quantitative methods to determine leak rate. Sandsten and Andersson (2012) used a block matching model and a velocity field model to quantify volume flow rates based on a sequence of images captured by an OGI camera. More recently, a new method called quantitative optical gas imaging (QOGI) was developed and has emerged as a commercially available method to fill the need for quantification using OGI (Zeng et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Detection limits of optical gas imagers as a function of temperature differential and distance

Zeng

Morris

2018

Journal of the Air & Waste Management Association

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Optical gas imaging (OGI) is an effective tool for detecting gas leaks from process equipment. Despite the fact that OGI has been used for leak detection for over a decade, its detection limit is an elusive performance metric and has not been systematically characterized and quantified like other detection instruments. A substantial body of research has been performed that has shed some light on the OGI detection limits and the factors that dictate the detection limits. The OGI detection limit expressed as ppm-m and ppm now can be quantified as a function of ΔT (differential temperature between the gas plume and the background), the OGI camera type, and the specific gas in question. Furthermore, the OGI detection limit expressed as grams per hour can be calculated based on the ΔT and the distance from the OGI camera to the leak location under common leak survey conditions. For the same OGI camera, the detection limit can vary by several orders of magnitude due to ΔT and distance. The present work has demonstrated how different OGI detection limits can be. More importantly, this work has, for the first time, formulated equations that can be used to determine OGI detection limits with a given set of leak detection conditions. Being able to quantify OGI detection limit and understand the variables that dictate the detection limit is a significant advancement. It will help OGI to become accepted as a mature field instrument. The variables characterized in this work should have an impact on the development of OGI leak survey protocols, such as Appendix K to Code of Federal Regulations 40 CFR Part 60 in the United States. Established detection limits will also help emission inventory for fugitive emissions when OGI is used as the sole leak detection method.Implications: Optical gas imaging (OGI) has been used for leak detection and control of fugitive volatile organic compound (VOC) emissions and methane emissions due to equipment leaks. However, detection limits of OGI have not been characterized and quantified like other detection instruments. The lack of well-understood detection limits has hindered broader applications of OGI. The work presented in this paper represents important steps that will enable OGI users and policymakers to establish (1) OGI detection limits under various conditions, (2) OGI leak survey criteria for a desired minimum detectable leak size, and (3) maximum potential emissions from the nondetect sources in emission inventory studies.

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Volume flow calculations on gas leaks imaged with infrared gas-correlation

Cited by 20 publications

References 13 publications

On the Viability of Video Imaging in Leak Rate Quantification: A Theoretical Error Analysis

On the Viability of Video Imaging in Leak Rate Quantification: A Theoretical Error Analysis

Optical Flow-Based Detection of Gas Leaks from Pipelines Using Multibeam Water Column Images

Detection limits of optical gas imagers as a function of temperature differential and distance

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