Infrared gas-filter correlation instrument for in situ measurement of gaseous pollutant concentrations

Herget, William F.; Jahnke, J. A.; Burch, Darrell E.; Gryvnak, David A.

doi:10.1364/ao.15.001222

Cited by 31 publications

(13 citation statements)

References 3 publications

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“…Thus, cross interference correction is necessary (Sayed and Mohamed, 2010;Bingham and Burton, 1984;Tyson et al, 1984;Lopez and Frutos, 1993). Most NDIR multi-gas analyzers use a look-up table, a matrix consisting of channel-to-channel interference constants, to correct cross interference (Herget et al, 1976;Jong et al, 2010;Dirk et al, 2009;Harold et al, 1999). However, the way of acquiring interference constants is different.…”

Section: Introductionmentioning

confidence: 99%

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

et al. 2013

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In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to in situ monitor stack emissions. The proposed algorithm simultaneously compensates for nonlinear absorption and cross interference among different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The proposed algorithm is derived from a classical one and uses interference functions to quantify cross interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO₂ and CO) serves as an example for the validation of the proposed algorithm. The interference functions in this case can be obtained by least-squares fitting with third-order polynomials. Experiments show that the results of cross interference correction are improved significantly by utilizing the fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO₂ and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial analyzer with high accuracy was used to validate the CO and CO₂ measurements derived from the NDIR analyzer prototype in which the new algorithm was embedded. The comparison of the two analyzers show that the prototype works well both within the linear and nonlinear ranges

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Section: Introductionmentioning

confidence: 99%

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

et al. 2013

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“…Due to the narrow bandwidth and the elaborate spectrum of the target gas in the line of sight, the utilization of the target gas in the sample cell as a selective filter, and the differencing operation, GFCR provides highly specific detection of the intended gas. When the target gas is not present in the line of sight, the spectra of all other gases do not correlate with the absorption of the sample cell; therefore, the net GFCR signal is zero, corresponding to zero correlation 5,6 . In this manner, the GFCR technique provides a highly sensitive method of quickly measuring the quantity of a target gas species in a multi-gas sample with a simple differental measurement.…”

Section: Gas Filter Correlation Radiometrymentioning

confidence: 99%

<title>University of Virginia suborbital infrared sensing experiment</title>

et al. 2002

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An Orion sounding rocket launched from Wallops Flight Facility carried a University of Virginia payload to an altitude of 47 km and returned infrared measurements of the Earth's upper atmosphere and video images of the ocean. The payload launch was the result of a three-year undergraduate design project by a multi-disciplinary student group from the University of Virginia and James Madison University. As part of a new multi-year design course, undergraduate students designed, built, tested, and participated in the launch of a suborbital platform from which atmospheric remote sensors and other scientific experiments could operate. The first launch included a simplified atmospheric measurement system intended to demonstrate full system operation and remote sensing capabilities during suborbi tal flight. A thermoelectrically cooled HgCdTe infrared detector, with peak sensitivity at 10 µm, measured upwelling radiation and a small camera and VCR system, aligned with the infrared sensor, provided a ground reference. Additionally, a simple orientation sensor, consisting of three photodiodes, equipped with red, green, and blue light with dichroic filters, was tested. Temperature measurements of the upper atmosphere were successfully obtained during the flight. Video images were successfully recorded on-board the payload and proved a valuable tool in the data analysis process. The photodiode system, intended as a replacement for the camera and VCR system, functioned well, despite low signal amplification.This fully integrated and flight tested payload will serve as a platform for future atmospheric sensing experiments. It is currently being modified for a second suborbital flight that will incorporate a gas filter correlation radiometry (GFCR) instrument to measure the distribution of stratospheric methane and imaging capabilities to record the chlorophyll distribution in the Metompkin Bay as an indicator of pollution runoff.

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“…In general, a commercial multi-gas analyzer (e.g., Model 60i made by Thermo Fisher Scientific or Li-7500 made by Li-Cor) specifies a particular application where the intended and interfering channels lie within linear ranges. Thus, cross-interference can be corrected through the conventional look-up table (consisting of various constant factors quantifying gas-to-gas interferences) approach (Herget et al, 1976;Jacob and Roy, 2012;Dirk et al, 2009;Harold et al, 1993). In this case, SO 2 concentrations within a certain linear range can be well resolved.…”

Section: Introductionmentioning

confidence: 99%

Industrial SO<sub>2</sub> emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm

et al. 2016

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Abstract. SO 2 variability over a large concentration range and interferences from other gases have been major limitations in industrial SO 2 emission monitoring. This study demonstrates accurate industrial SO 2 emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm. The proposed analyzer features a large dynamic measurement range and correction of interferences from other coexisting infrared absorbers such as NO, CO, CO 2 , NO 2 , CH 4 , HC, N 2 O, and H 2 O. The multichannel gas analyzer measures 11 different wavelength channels simultaneously to correct several major problems of an infrared gas analyzer including system drift, conflict of sensitivity, interferences among different infrared absorbers, and limitation of measurement range. The optimized algorithm uses a third polynomial instead of a constant factor to quantify gas-to-gas interference. Measurement results show good performance in the linear and nonlinear ranges, thereby solving the problem that the conventional interference correction is restricted by the linearity of the intended and interfering channels. The results imply that the measurement range of the developed multichannel analyzer can be extended to the nonlinear absorption region. The measurement range and accuracy are evaluated through experimental laboratory calibration. Excellent agreement was achieved, with a Pearson correlation coefficient (r 2 ) of 0.99977 with a measurement range from approximately 5 to 10 000 ppmv and a measurement error of less than 2 %. The instrument was also deployed for field measurement. Emissions from three different factories were measured. The emissions of these factories have been characterized by different coexisting infrared absorbers, covering a wide range of concentration levels. We compared our measurements with commercial SO 2 analyzers. Overall, good agreement was achieved.

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Infrared gas-filter correlation instrument for in situ measurement of gaseous pollutant concentrations

Cited by 31 publications

References 3 publications

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

<title>University of Virginia suborbital infrared sensing experiment</title>

Industrial SO<sub>2</sub> emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm

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Infrared gas-filter correlation instrument for in situ measurement of gaseous pollutant concentrations

Cited by 31 publications

References 3 publications

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

<title>University of Virginia suborbital infrared sensing experiment</title>

Industrial SO&lt;sub&gt;2&lt;/sub&gt; emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm

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Industrial SO<sub>2</sub> emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm