Issues related to LNG tank cooling
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The storage tank is cooled using LNG; the entry of LNG causes the temperature of the tank to drop and its pressure to decrease, while the heat absorption during the vaporization of LNG leads to an increase in the tank’s pressure. Find the local instantaneous pressure changes during the cooling process of the storage tank.
And how much LNG is required to cool a 100,000 m3 storage tank?
Cool it with liquid nitrogen – it’s cheap, effective, and safe
It is recommended to use liquid nitrogen for the purging of LNG storage tanks and cooling the tanks~~
After cooling with liquid nitrogen, is the nitrogen then replaced with LNG?
In my understanding, when LNG first enters the system, it vaporizes rapidly due to the large temperature difference, which is mainly manifested as an increase in pressure. As the amount of LNG increases and the temperature difference inside the tank decreases, it is primarily manifested as a decrease in pressure.
After cooling with liquid nitrogen, it is then replaced with LNG. Even if you have conducted pressure and airtightness tests, it’s impossible to be sure that no problems will arise at low temperatures; therefore, liquid nitrogen must be used, as it is both safe and economical.
I don’t quite understand why using liquid nitrogen makes things safe when there’s a problem
This post was last edited by xjonlyyou on 2017-10-11 at 19:17. LNG is a flammable and hazardous liquid that can catch fire and explode. Liquid nitrogen, on the other hand, does not, so it is safe. Of course, a large leak of liquid nitrogen can be fatal if you happen to be in the vicinity, due to the low temperatures or suffocation; therefore, safety is also relative.
Generally, the low-temperature BOG from LNG carriers is used to pre-cool the storage tanks. When the temperature reaches around -80°C, LNG is fed into the tank through specialized pre-cooling nozzles, which spray it throughout the entire tank volume, thereby reducing the vaporization of LNG and the resulting waste of BOG. Moreover, LNG storage tanks generally have two feed pipelines. It will cause the space inside the storage tank to cool down evenly. Avoid sudden changes in temperature and pressure.
Your reply was very helpful to me, thank you