Abstract
Stratification or the creation of two convectively stable layers of liquids with different densities is the beginning of events leading to possible roll-over.
The main factors are the convective mechanism whereby heat inflows into the lower layer become locked into that layer causing its temperature to rise and density to fall with time; also the preferential evaporation of methane from the upper layer of LNG (or propane from stratified LPG) will lead to an increase in density with time; also the heat of mixing is large and may evaporate up to 10 % of the liquid mixtures.
The chapter discusses how stratification can be prevented, and/or removed, by adequate mixing operations. However, auto-stratification after filling is possible and needs to be countered by mixing at a later time.
The chapter concludes with some advisory points towards anticipating roll-over, if the mixing is insufficient, or too late, to remove stratification.
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References
SIGTTO: Guidance for the Prevention of Rollover in LNG Ships. Witherby, Edinburgh (2013)
Booth, D.A., Bulsara, A., Joyce, F.G., Morton, I.P., Scurlock, R.G.: Wall film flow effects with LNG. Cryogenics 14, 562 (1974)
San Roman, O.: The dynamics of methane/ethane separation by differential surface tension driven flows; or the Marangoni effect. PhD thesis, Southampton University (1978)
Scurlock, R.G.: On-line instrumentation of cryogenic systems and plant to an accuracy of 0.01 % using cold electronics. In: Proc. ISA, Houston, vol. 32, p. 139 (1993)
Tchikou, A.: Mixing of propane and butane. PhD thesis, Southampton University (1985)
Voyteshonok, V.: Safe storage vessels for low-boiling liquids. Cold Facts 21, 33 (2005)
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Scurlock, R.G. (2016). Factors Creating Stratification: Management of LNG Rollover. In: Stratification, Rollover and Handling of LNG, LPG and Other Cryogenic Liquid Mixtures. SpringerBriefs in Energy. Springer, Cham. https://doi.org/10.1007/978-3-319-20696-7_6
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DOI: https://doi.org/10.1007/978-3-319-20696-7_6
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-20695-0
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