The Rollover Sequence of Events, Starting with Stratification

The Rollover Sequence of Events, Starting with Stratification 

Abstract The chapter concentrates on the sequence to be expected if stratification in LNG or LPG cannot be prevented. The natural convective heat flows into the stratified layers will lead to density equilibration between flie layers, when spontaneous mixing or roll-over may lead to a large rise in BOR. 

The management problems of preventing and/or handling roll-over are discussed in the light of previously recorded roU-over events and simulations. A major problem is the monitoring of all tanks, wifli limited instrumentation. Small effects like fall off in BOR, and rising liquid level from fliermal overfill, in individual tanks may be the only warning of stratification. 

Discussion of the spontaneous nnixing mechanism illustrates how the violent mixing depends on equilibration of two variables, temperature and composition, at the same time. In other words, roll-over is a property of cryogenic liquid mixtures, not single component cryogenic liquids. 

Roll-over is not unique to cryogenics, since oceanographers have met it in stratified sea waters with different temperature and salt content. 

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