scholarly journals Field Deployment of a Portable Optical Spectrometer for Methane Fugitive Emissions Monitoring on Oil and Gas Well Pads

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2707 ◽  
Author(s):  
Eric J. Zhang ◽  
Chu C. Teng ◽  
Theodore G. van Kessel ◽  
Levente Klein ◽  
Ramachandran Muralidhar ◽  
...  
Keyword(s):  
Near Infrared ◽  
Oil And Gas ◽  
Tunable Diode Laser ◽  
Angle Of Arrival ◽  
Good Correspondence ◽  
Laser Absorption ◽  
Deviation Analysis ◽  
Single Sensor ◽  
Field Deployment

We present field deployment results of a portable optical absorption spectrometer for localization and quantification of fugitive methane (CH4) emissions. Our near-infrared sensor targets the 2ν3 R(4) CH4 transition at 6057.1 cm−1 (1651 nm) via line-scanned tunable diode-laser absorption spectroscopy (TDLAS), with Allan deviation analysis yielding a normalized 2.0 ppmv∙Hz−1/2 sensitivity (4.5 × 10−6 Hz−1/2 noise-equivalent absorption) over 5 cm open-path length. Controlled CH4 leak experiments are performed at the METEC CSU engineering facility, where concurrent deployment of our TDLAS and a customized volatile organic compound (VOC) sensor demonstrates good linear correlation (R2 = 0.74) over high-flow (>60 SCFH) CH4 releases spanning 4.4 h. In conjunction with simultaneous wind velocity measurements, the leak angle-of-arrival (AOA) is ascertained via correlation of CH4 concentration and wind angle, demonstrating the efficacy of single-sensor line-of-sight (LOS) determination of leak sources. Source magnitude estimation based on a Gaussian plume model is demonstrated, with good correspondence (R2 = 0.74) between calculated and measured release rates.

Gaseous Contaminant Measurement for Semiconductor Processing by Diode Laser Spectroscopy

1995 ◽  
Vol 38 (5) ◽  
pp. 22-29
Author(s):  
James McAndrew ◽  
Ronald Inman ◽  
Benjamin Jurcik
Keyword(s):  
Diode Laser ◽  
Fluid Dynamic ◽  
Air Separation ◽  
Tunable Diode Laser ◽  
Laser Absorption ◽  
Diode Laser Spectroscopy ◽  
Diode Laser Absorption ◽  
Gaseous Contaminant

Tunable diode laser absorption spectroscopy (TDLAS) is a novel tool for purity measurement in microelectronic process gases and environments. It is compatible with any matrix gas and extremely sensitive. This paper describes the application of a laboratory TDLAS instrument to measurement of CO, CO2, and H2O with sub-ppb sensitivity, including determination of a CO level of 0.35± 0.2 ppb in nitrogen samples from an air separation plant. Fluid dynamic simulation was used to optimize the design of the cell used for H20 measurements. TDLAS lends itself to the study of contamination sources in situ. As examples, measurements of CO generation in sampling vessels and of CO2 outgassing in an electropolished stainless steel chamber are briefly discussed.

scholarly journals Mathematical Methods and Algorithms for Improving Near-Infrared Tunable Diode-Laser Absorption Spectroscopy

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4295 ◽  
Author(s):  
Tianyu Zhang ◽  
Jiawen Kang ◽  
Dezhuang Meng ◽  
Hongwei Wang ◽  
Zhengming Mu ◽  
...  
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Tunable Diode Laser ◽  
Molecular Absorption ◽  
Laser Absorption Spectroscopy ◽  
Mathematical Methods ◽  
Laser Absorption ◽  
Optical Paths ◽  
Diode Laser Absorption

Tunable diode laser absorption spectroscopy technology (TDLAS) has been widely applied in gaseous component analysis based on gas molecular absorption spectroscopy. When dealing with molecular absorption signals, the desired signal is usually interfered by various noises from electronic components and optical paths. This paper introduces TDLAS-specific signal processing issues and summarizes effective algorithms so solve these.

scholarly journals Determination of CO2 Content in the Headspace of Spoiled Yogurt Packages

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Bojana Danilović ◽  
Dragiša Savić ◽  
Lorenzo Cocola ◽  
Massimo Fedel ◽  
Luca Poletto
Keyword(s):  
Tunable Diode Laser ◽  
Food Storage ◽  
Slow Increase ◽  
Microbial Spoilage ◽  
Laser Absorption ◽  
Candida Kefyr ◽  
Rapid Accumulation ◽  
And Control ◽  
Diode Laser Absorption

The CO2 formation during food storage can often be correlated with the increase in yeast population. Yogurt and other dairy products are susceptible to yeast contamination. Accumulation of CO2 in the headspace of yogurt packages can lead to the eventual blowing off of the package. Therefore, determination of CO2 in the yogurt packages can indicate eventual unsafety of the product. The aim of this paper was to determine CO2 concentration in the headspace of different yogurt containers contaminated with yeast at the levels of 1 and 5 CFU/ml. Yeast Candida kefyr, previously isolated from spoiled yogurt, was used for contamination. Contaminated and control samples of yogurt were incubated at 30°C. A device based on tunable diode laser absorption spectroscopy was used for the measurement of CO2 concentration. The CO2 content in all analysed samples changed in a similar manner with slow increase to the value of 6% during the first 30 h and, after that, rapid accumulation to 17–20%. The initial level of yeast contamination did not have significant influence to the CO2 content trend. The increase in the number of yeast was observed after 10 h of incubation, and the final value of 6-7 log·CFU/cm3 was reached after 40 h of incubation. The significant increase in the yeast number can be correlated with the CO2 content in a way that CO2 concentration of 6% can be considered as critical for microbial spoilage. Since the TDLAS technique is simple and nondestructive, it can be a promising possibility for detection of the microbial spoilage in food.

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