METHOD FOR THE REAL-TIME DETERMINATION OF THE FILLING LEVEL OF A CRYOGENIC TANK

摘要

The invention relates to a method for the real-time determination of the filling level of a cryogenic tank (1) intended to house a two-phase liquid/gas mixture, in which at least one of the following variables is calculated for the liquid and optionally for the gas at each time step (t, t+ ?t...), namely: the level, volume or mass contained in the tank (1), whereby, at each time step, the method includes the measurement of the pressure differential (DP=PB-PH) (in Pa) between the upper and lower parts of the tank and at least one of the pressures (PH, PI) of said differential. The invention is characterised in that the method includes the following steps: use of a thermal model at each time step (t, t+ ?t...) to calculate the average temperatures of the liquid (Tl) and the gas (Tg) in the tank (1) on the basis of the measured pressure differential (PB-PH) and at least one of the pressures (PH, PI) of said differential; calculation of the change over time (t, t+ ?t...) in at least the density of the liquid (pl) (in kg/m3) on the basis of the average temperature of the liquid (Tl) and the pressures (PH) (PB) in the tank; calculation of the liquid level (hl) (in m) in the tank (1) by applying the general law of hydrostatics to the liquid, of type dP=- pl.g.dhl, on the basis of the calculated liquid density (pl) (wherein dP is the liquid pressure variation, pl is the density of the liquid, g is ground acceleration and dhl is the variation in the height of the liquid).