The main purpose of this is to simulate it on hysys but on the LNG regasification process I dont know how to maintain steady the pressure of the tankt adding a gas like N2 to make the pressure steady. The idea is very simple: a tank full of LNG (liquid natural gas), lets say that 90% of the tank is full with lng and the rest is ng (natural gas), so if I wanna take out the lng off the tank to be sent to the regasification sector, how is that I can keep the tank pressure steady?

the only idea that I can think off, its to blow back to the tank part of the regasified lng, but I supose that I would need some sort of NG back up/storage to be added to the LNG tank while the lng is starting to get gasified.

Thanks