Research article: Enhancement of the revised Klosek and McKinley method for density calculations of LNG

Enhancement of the revised Klosek and McKinley method for density calculations of liquefied natural gas (LNG) over the temperature range from (100 to 135) K at pressures up to 10 MPa

By Christopher Tietz, Markus Richter, Reiner Kleinrahm and Roland Span

Abstract:
The revised Klosek and McKinley (RKM) method is a well-established model for the calculation of saturated liquid densities within the field of liquefied natural gas (LNG) custody transfer. Due to pressures higher than the vapor pressure in pipes from tanks to transfer stations, the densities resulting from this easy-to-use approach often deviate from the true density of the compressed liquid phase. However, higher pressures are typical for pipe flows in receiving terminals. Therefore, the applicability of the RKM method was expanded with the most recent highly accurate (p, ρ, T, x) data sets for six compressed LNG mixtures measured with a special densimeter for cryogenic liquid mixtures. The newly developed enhanced RKM (ERKM) method now enables density calculations of LNG mixtures at pressures up to 10 MPa, and the temperature restriction of the RKMmethod (T b 115 K) was expanded to reach temperatures up to 135 K. The estimated expanded uncertainty (k = 2) of the newly developed equation is 0.10% for the temperature range from (100 to 115) K and 0.15% for temperatures between (115 and 135) K at pressures up to 10MPa. Further restrictions of the method are basically the same as for the RKM method and are specified in more detail within the present paper.

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