LIQUID DENSITY MEASURING APPARATUS IN LNG TANK

摘要

PROBLEM TO BE SOLVED: To achieve an accurate measurement free from the effect of composition and temperature changes by a method wherein two each of a plurality of connecting pieces are selected sequentially with lower ends thereof opened at different heights within LNG to supply a gas and a liquid density between the lower ends is calculated from a differential pressure measured. SOLUTION: A plurality of connecting pieces 12 are so arranged to have lower ends 13b opened at different heightsΔh from a liquid level in LNG/and a difference (h) between the heights is fixed. A differential pressure sensor 14 has pressure introduction ports 14a and 14b and is set corresponding to the liquid density of the LNG to measure the differential pressure. A changeover communication means 16 sequentially selects two each of the connecting pipes 12 to make the upper ends 13a communicate respectively with pressure introduction ports 14a and 14b of the differential pressure sensor 14. A gas supplier 18 has a constant flow rate valve 18a to supply a gas at the same flow rate separately to the two connecting pipes 12a and 12b. This enables the equalization of a pressure loss as caused by gas flows within the connecting pipes 12 thereby lowering the service quantity of the gas 2 with a smaller size of the apparatus. This can minimize the agitation of the LNG by the gas 2.