Simplified calibration methodology of chromatographs used in custody transfer measurements of natural gas

• Autorzy: Oliveira E. C.
• Języki publikacji: PL

Abstrakty

EN

The properties, superior calorific value (SCV) and the compressibility factor (z), of 77 natural gas (NG) samples are calculated from two different calibration approaches of gas chromatography, based on ISO 6974-2. The method A uses an analytical curve with seven points that the best adjust is confirmed by Analysis of Variance (ANOVA); it is required when the composition of the natural gas varies. The method B uses a single point calibration, with an allowed tolerance between the calibration gas mixture and sample mole fraction, so it is used to analyze constant natural gas streams. From natural gas composition analyzed by both methods, exceeding the method B allowed tolerance; SCV, z and its uncertainties are calculated and compared. The results show that all samples that comply with Brazilian legislation can be analyzed by method B, because there are no metrological differences in terms of SCV and z, even though the allowed tolerance has been exceeded. This simplified methodology minimizes operator exposure, besides saving about US$ 50,000.00 per chromatograph.

Słowa kluczowe

EN

simplified calibration; gas chromatography; superior calorific value; compressibility factor; natural gas

• Wydawca: Komitet Metrologii i Aparatury Naukowej PAN
• Czasopismo: Metrology and Measurement Systems
• Rocznik: 2012
• Tom: Vol. 19, nr 2
• Strony: 405--416
• Opis fizyczny: Bibliogr. 12 poz., tab., wykr., wzory

Twórcy

autor

Oliveira E. C.

• Petrobras Transporte S.A., Project Management, Av. Presidente Vargas, 328, 20091-060 Rio de Janeiro - RJ, Brazil,

Bibliografia

• [1] Analytical Methods Committee. (1995). Uncertainty of measurement – implications of its use in analytical science. Analyst, 120, 2303-2308.
• [2] International Organization for Standardization (ISO). (1993). Guide to the Expression of Uncertainty in Measurement, ISO: Geneva, Switzerland.
• [3] Bich, W., Cox, M.G., Harris, P.M. (2006). Evolution of the ‘Guide to the Expression of Uncertainty in Measurement’. Metrology, 43, S161-S166.
• [4] Cox, M.G., Harris, P.M. (2006). Measurement uncertainty and traceability. Meas. Sci. Technol., 17, 533-540.
• [5] EURACHEM/CITAC Guide. (2000). Quantifying Uncertainty in Analytical Measurement, 2nd ed., Ellison, S.L.R., Rosslein, M., Williams, A., Eds., EURACHEM/CITAC: Hungary.
• [6] ISO 6974-2:2001. (2006). Natural gas - Determination of composition with defined uncertainty by gas chromatography - Part 2: Measuring-system characteristics and statistics for processing of data. International Organization for Standardization: Geneva, Switzerland.
• [7] Wang, D., Wang, S., Zhao, S. (2005). Estimation of the Uncertainty of Fe in Metallic Silicon Determined by Inductively Coupled Plasmas-Atomic Emission Spectroscopy. J. Test. Eval., 33, 3-7.
• [8] Miller, J.N., Miller, J.C. (2005). Statistics and chemometrics for analytical chemistry, 5th ed.; Prentice Hall, New York.
• [9] Oliveira, E.C. (2011). Critical metrological evaluation of fuels analyses by measurement uncertainty. Metrol. Meas. Syst., 18(2), 235-248.
• [10] Oliveira, E.C. (2006). Metrology of natural gas: Evaluation of uncertainty of their physicochemical properties. In Rio Oil and Gas Expo and Conference. (in Brazil)
• [11] ISO 6976:1995. (1995). Natural gas - Calculation of calorific values, density, relative density and Wobbe index from composition. International Organization for Standardization: Geneva, Switzerland.
• [12] National Agency of Petroleum. Natural Gas and Biofuels.(2008). Resolution No. 16. (in Brazil)