Method and system for the real-time calculation of the amount of energy transported in a non-refrigerated, pressurised, liquefied natural gas tank

A method for real-time calculation of residual chemical energy E contained in a pressurised tank defined by its shape and its dimensions and containing a layer of liquefied natural gas, the layer of liquefied natural gas being defined at a given instant t, by its temperature T, its density ρ, and its level h in the tank,

• the method including an algorithm that, at a given instant t, comprises:
• acquiring the characteristic parameters of the layer of liquefied natural gas by measurement,
• of the level h of the layer of liquefied natural gas in the tank, using a level sensor,
• of the temperature T using a temperature sensor, and
• of the density ρ using a density sensor;
• and
• determining the total mass mt of the liquefied natural gas contained in the tank, wherein the algorithm, for each instant t, further comprises:
• calculating of the mass gross calorific value GCVmass of the liquefied natural gas using a function f taking as parameters the temperature and the density ρ of the liquid according to the formula:
• GCVmass=f(T,ρ);
• and
• calculating of the residual chemical energy E according to the formula:
• E=GCVmass*mt
• wherein the function f that connects the mass gross calorific value GCVmass to die parameters T and ρ is according to the formula:
• f(T,ρ)=A(T)+B*p
• where,
• A is a constant value for a given temperature, and
• B is a constant independent of the composition.