Liquefied petroleum gas subsea storage system - water pressure maintains the gas liquefied on the sea bed

摘要

A vessel and procedure is described for the storage on the sea bed of liquefied petroleoum gas product (butane, propane) whose critical temperature is above the ambient sea water temperature. The vessels are modular rectangular towable barges of up to 25,000m3 capacity in steel, concrete or plastic with separate compartments for liquid storage, ballast and floatation. Filling is carried out by displacing downwards the water already in the vessel; this automatically re-enters as the liquid is drawn off during emptying. The compartments containing the liquefied petroelum gas is in communication with the surrounding water such that the water pressure is above the saturated vapour pressure of the product so that the product will remain liquefied.