I would like to ask why, in LNG storage tanks, there is a region of lower density at the bottom, causing the liquid to roll upward naturally
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I would like to ask why, in LNG storage tanks, there is a region of lower density at the bottom, causing the liquid to roll upward naturally
The differences in temperature and density that occur within LNG lead to stratification (with each layer having different temperature and density), and relative flow occurs between these layers. If the temperature at the bottom is high, a large amount of gas will escape as it moves upward, resulting in overpressure, which is very dangerous for storage tanks.
Aren’t there compressors with circulation? ? ?
1. The volume of a single large LNG tank is generally 80,000 cubic meters or 160,000 cubic meters (or even 320,000 cubic meters); it has a relatively high height, which creates the conditions for stratification to occur； 2. The gas source purchased in large tanks (the methane content) is not always consistent; the density varies naturally depending on the source, creating conditions for density differences ； 3. During long-term storage, heat input provides the internal drive for the formation of layers with different heights and densities.
Due to differences in nitrogen content, as well as temperature and pressure during unloading, the density varies!
Long-term storage causes stratification of the LNG liquid, with the lower layer having a higher density.