Issues with liquid inlet at the top and bottom of LNG storage tanks
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What is the difference between upper and lower inlet ports in LNG storage tanks? How should large vent volumes from storage tanks be adjusted? We provide atmospheric pressure storage tanks
It seems there’s an explanation for this issue in the design specifications
The downward flow of liquid can thoroughly cool the LNG, reducing evaporation； The liquid entering the tank at the top is prone to vaporization, increasing the amount that needs to be vented from the tank ； Properly operate the storage tank; when the amount of liquid drained from the tank is large, check its insulation.
Then the person upstairs said that insulation is one aspect; if possible, measure the temperature of the liquid and compare it with the temperature inside the storage tank. If the temperature difference is small, there’s no need to add more liquid, as this would increase the amount of vaporization.
The liquid fed from above can reduce the pressure at the upper level, allowing for faster unloading of the LNG tankers as more liquid is unloaded; the liquid fed from below allows the LNG to enter directly to the bottom of the storage tank. There is no top-to-bottom evaporation process, so the unloading is relatively smooth and slow. When the tank level is low, it is recommended that you use inflow to ensure that as much liquid as is added is stored. However, when LNG with different components enters a tank, the liquid with a lower density enters from the bottom while that with a higher density enters from the top, to prevent rolling!
If the volatility is high, there might be a problem with adiabaticity
For our LNG, the manufacturer assigns dedicated personnel to oversee it; we haven’t explored this aspect in detail yet
The feed liquid is generally used when the tank is empty； Function: The feed line is usually equipped with a spraying device that can pre-cool the cylinder, preventing uneven heating of the cylinder; however, this increases the amount of vent gas. Lowering the inlet liquid level can reduce the amount of venting.
The incoming liquid will reduce the evaporation of LNG in the storage tank, thereby lowering the tank pressure. You can give it a try.
Isn’t the feed liquid meant to act as a spray for liquefied NG? Why then is it said that the feed liquid vaporizes easily? I don’t understand, please advise:o