Does tank pressure refer to the vapor phase pressure or the liquid phase pressure?
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Pressure requirements for the company’s LNG storage tanks
Oh, I see now. 0.38 MPa refers to the pressure in the gas phase; the pressure in the liquid phase is not constant, as it depends on the liquid level and the location where the pressure is measured. Oh, what a shame; my brain froze up and I couldn’t solve such a simple question. I’m sorry for wasting everyone’s time.
The design pressure of a device is the pressure at the top of the device.
The pressure of the gas-liquid mixture is the same!
Should the static pressure of the liquid column be taken into consideration, at the top or at the bottom?
If the pressure at the top of the tank refers to the gas phase pressure at the tank top； If it is the pressure at the bottom of the tank, then it is the pressure of the liquid phase inside the tank!
It’s mainly the gas pressure at the top
For partially vaporized medium storage tanks, the pressure refers to the normal pressure at the top of the tank, that is, the pressure when there is a portion of liquid stored inside the tank. For such liquefied gas tanks, the pressure at the top of the tank and the liquid level inside it need to be monitored. With these two values, it is possible to determine the pressure at the bottom of the tank as well. In addition, the temperature of the tank also needs to be monitored; some tanks are equipped with cooling systems via spraying to prevent the liquid inside from vaporizing too much and causing excessive pressure in the tank.
Well, yes, I learned more about it – there are multiple pressure sensors located at various points on the tank, such as the top and bottom. The tank pressure refers to the pressure in the gas phase at the upper part of the tank; additionally, the pressure at the bottom of the liquid phase also needs to be measured. By calculating the difference between these two pressures, it’s possible to easily determine the liquid level in the tank. Thank you for your answer.