Density measurements of liquefied natural gas (LNG) over the temperature range from (105 to 135) K at pressures up to 8.9 MPa. (September 2017)

• Record Type: Journal Article
• Authors: Lentner, Rafael; Richter, Markus; Kleinrahm, Reiner; Span, Roland
• Is Part Of: Journal of chemical thermodynamics. Volume 112(2017)
• Page Start: 68
• Page End: 76
• Publication Date: 2017-09
• Subjects: Cryogenic liquid mixtures -- Density measurement -- Single-sinker densimeter -- Liquefied natural gas (LNG) -- Magnetic suspension coupling -- Synthetic gas mixtures; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2017.04.002
• Languages: English
• ISSNs: 0021-9614

Abstract

Graphical abstract: Highlights: Densities of LNG were measured with very high accuracy. A special single-sinker densimeter with magnetic suspension coupling was used. Detailed comparisons with the GERG-2008 equation of state are presented. Saturated liquid densities were also compared with other models (RKM, COSTALD). Experimental saturated liquid densities agree best with the RKM method. Abstract: The ( p, ρ, T, x ) behaviour of five different synthetic liquefied natural gas (LNG) mixtures was investigated over the temperature range from (105 to 135) K at pressures up to 8.9 MPa utilizing a single-sinker magnetic suspension densimeter for cryogenic liquid mixtures. Due to the supercritical liquefaction procedure and the integration of a special VLE-cell, it was possible to measure densities in the homogeneous liquid phase of LNG without changing the composition. The mixtures were prepared gravimetrically and then analysed by gas chromatography according to highest metrological standards. The relative combined expanded uncertainty ( k = 2) in density considering all effects, including the uncertainty in composition, was approximately 0.044% for all measurements. Comparisons of the new experimental data to the GERG-2008 equation of state for natural gas mixtures revealed clear and systematic deviations up to 0.22%. The reported uncertainty for the GERG-2008 equation is (0.1 to 0.5)% for the conditions considered, thus, all measured densities are represented well within this uncertainty range. Comparisons to density calculation methods often used in LNG industry, such as the revised Klosek and McKinley method as well as the COSTALD correlation, revealed that the quality of the calculations clearly depends on the pressure range and on the composition of the LNG mixture.