Trace moisture measurement in natural gas mixtures with a single calibration for nitrogen background gas

The feasibility of using Raman spectrometry for determining the composition of mixtures of natural gas components was examined. Raman intensity measurements were carried out on eight, gravimetrically prepared, binary gas mixtures containing methane, nitrogen, and isobutane at ambient temperature and at pressures to 0.8 MPa. The repeatability of the molar intensity ratio, ( I2/ y2)/( I1/ y1), where y1 is the concentration of component 1 in the mixture, and I1 is the intensity of the related line in the mixture spectrum, was examined. The compositions of two gravimetrically prepared methane-nitrogen-isobutane gas mixtures were determined spectrometrically with an estimated precision of about 0.001 in the mole fraction. Typical differences from the gravimetric concentrations were less than 0.002 in the mole fraction. The Raman spectrum of a gravimetrically prepared, eight component, hydrocarbon gas mixture was obtained to show that the Raman spectrometric method has potential for being applicable to natural gas type mixtures.

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Validation of spectroscopic gas analyzer accuracy using gravimetric standard gas mixtures: Impact of background gas composition on CO<sub>2</sub> quantitation by cavity ring-down spectroscopy

10.5194/amt-2017-54 ◽

2017 ◽

Cited By ~ 1

Author(s):

Jeong Sik Lim ◽

Miyeon Park ◽

Jinbok Lee ◽

Jeongsoon Lee

Keyword(s):

Ambient Air ◽

Gas Mixtures ◽

Gas Composition ◽

Optical Intensity ◽

Negative Deviation ◽

Gas Analyzer ◽

Pressure Broadening ◽

Background Gas ◽

Standard Gas Mixtures ◽

Cavity Ring Down

Abstract. Effect of background gas composition on the measurement of CO2 levels was investigated by wavelength-scanned cavity ring-down spectrometry (WS-CRDS) employing a spectral line centered at the R(1) of the (3 0° 1)III ← (0 0 0) band. For this purpose, eight cylinders with various gas compositions were gravimetrically and manometrically prepared within 2σ = 0.1 %, and these gas mixtures were introduced into the WS-CRDS analyzer calibrated against standards of ambient air composition. Depending on the gas composition, deviations between CRDS-determined and gravimetrically (or manometrically) assigned CO2 concentrations ranged from −9.77 to 5.36 μmol/mol, e.g., excess N2 exhibited a negative deviation, whereas excess Ar showed a positive one. The total pressure broadening coefficients (TBPCs) obtained from the composition of N2, O2 and Ar thoroughly corrected the deviations up to −0.5–0.6 μmol/mol, while these values were −0.43–1.43 μmol/mol considering PBCs induced by only N2. The use of TBPCs enhanced deviations to be corrected to ~ 0.15 %. Furthermore, the above correction linearly shifted CRDS responses for a wide extent of TPBCs ranging from 0.065 to 0.081 cm−1 atm−1. Thus, accurate measurements using optical intensity-based techniques such as WS-CRDS require TBPC-based instrument calibration.

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Thermophysical Properties of Natural Gas Mixtures Derived from Acoustic Cavity Measurements

ACS Symposium Series - Supercritical Fluid Engineering Science ◽

10.1021/bk-1992-0514.ch010 ◽

1992 ◽

pp. 121-132

Author(s):

S. O. Colgate ◽

A. Sivaraman

Keyword(s):

Natural Gas ◽

Thermophysical Properties ◽

Gas Mixtures ◽

Acoustic Cavity

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Capturing the Effects of NOX and SOX Impurities on Oxy-Combustion Under Supercritical CO2 Conditions for Coal-Derived Syngas and Natural Gas Mixtures

10.1115/1.0002639v ◽

2021 ◽

Author(s):

Ramees K Rahman ◽

K R v (Raghu) Manikantachari ◽

Samuel Barak ◽

Erik Ninnemann ◽

Ashvin Hosangadi ◽

...

Keyword(s):

Natural Gas ◽

Supercritical Co2 ◽

Gas Mixtures

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Ignition Studies of C1-C7 Natural Gas Blends At Gas-Turbine Relevant Conditions

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4050063 ◽

2021 ◽

Author(s):

Amrit Sahu ◽

A.A.E.S Mohamed ◽

Snehashish Panigrahy ◽

Gilles Bourque ◽

Henry Curran

Keyword(s):

Natural Gas ◽

Gas Turbine ◽

Gas Mixtures ◽

Rapid Compression Machine ◽

Temperature Range ◽

Auto Ignition ◽

Wide Range ◽

Model Predictions ◽

Detailed Kinetic Model ◽

Sensitization Effect

Abstract New ignition delay time measurements (IDT) of natural gas mixtures enriched with small amounts of n-hexane and n-heptane were performed in a rapid compression machine to interpret the sensitization effect of heavier hydrocarbons on auto-ignition at gas-turbine relevant conditions. The experimental data of natural gas mixtures containing alkanes from methane to n-heptane were carried out over a wide range of temperatures (840-1050 K), pressures (20-30 bar), and equivalence ratios (f = 0.5 and 1.5). The experiments were complemented with numerical simulations using a detailed kinetic model developed to investigate the effect of n-hexane and n-heptane additions. Model predictions show that the addition of even small amounts (1-2%) of n-hexane and n-heptane can lead to an increase in reactivity by ~40-60 ms at a temperature of 700 K. The IDTs of these mixtures decrease rapidly with an increase in the concentration of up to 7.5% but becomes almost independent of the C6/C7 concentration >10%. This sensitization effect of C6 and C7 is also found to be more pronounced in the temperature range 700-900 K compared to that at higher temperatures (>900 K). The reason is attributed to the dependence of IDT primarily on H2O2(+M)??H+?H (+M) at higher temperatures while the fuel-dependent reactions such as H-atom abstraction, RO2 dissociation, or Q OOH+O2 reactions are less important compared to the temperature range 700-900 K, where they are very important.

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Ignition Studies of C1–C7 Natural Gas Blends at Gas-Turbine Relevant Conditions

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2020-15826 ◽

2020 ◽

Author(s):

Amrit Bikram Sahu ◽

A. Abd El-Sabor Mohamed ◽

Snehasish Panigrahy ◽

Gilles Bourque ◽

Henry Curran

Keyword(s):

Natural Gas ◽

Gas Turbine ◽

Ignition Delay ◽

Delay Time ◽

Ignition Delay Time ◽

Gas Mixtures ◽

Auto Ignition ◽

Wide Range ◽

Detailed Kinetic Model ◽

Sensitization Effect

Abstract New ignition delay time measurements of natural gas mixtures enriched with small amounts of n-hexane and n-heptane were performed in a rapid compression machine to interpret the sensitization effect of heavier hydrocarbons on auto-ignition at gas-turbine relevant conditions. The experimental data of natural gas mixtures containing alkanes from methane to n-heptane were carried out over a wide range of temperatures (840–1050 K), pressures (20–30 bar), and equivalence ratios (φ = 0.5 and 1.5). The experiments were complimented with numerical simulations using a detailed kinetic model developed to investigate the effect of n-hexane and n-heptane additions. Model predictions show that the addition of even small amounts (1–2%) of n-hexane and n-heptane can lead to increase in reactivity by ∼40–60 ms at compressed temperature (TC) = 700 K. The ignition delay time (IDT) of these mixtures decrease rapidly with an increase in concentration of up to 7.5% but becomes almost independent of the C6/C7 concentration beyond 10%. This sensitization effect of C6 and C7 is also found to be more pronounced in the temperature range 700–900 K compared to that at higher temperatures (> 900 K). The reason is attributed to the dependence of IDT primarily on H2O2(+M) ↔ 2ȮH(+M) at higher temperatures while the fuel dependent reactions such as H-atom abstraction, RȮ2 dissociation or Q.OOH + O2 reactions are less important compared to 700–900 K, where they are very important.

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