Liquid storage systems

#This invention relates generally to systems for storing liquids and more particularly to a petroleum storage structure utilizing earthen walls and floor for the major portion of the structure.

#Conventional petroleum storage usually involves fabricated metal storage tanks. Such storage of petroleum is feasible where the storage is relatively temporary such as where the petroleum stored is in transit either for refining or for distribution by tanker, barge or ground transport.

#Since the "Energy Crisis" incurred by the producing countries' oil boycott of 1974, there has been substantial concern that future crises will be precipitated by similar boycotts by oil producing nations. To avoid this President Ford has required that a substantial amount of crude oil be placed in storage in this country. This requirement has imposed a great deal of pressure to develop suitable storage capability for this inventory of petroleum. Among the suggested storage receivers are the salt domes which occur in certain parts of the country. The salt domes, although more economical then fabricated tanks, do have limitations in that their availability is restricted to certain geographical locations and do impose some pumping costs for injecting and recovering the petroleum from the formations.

#FIG. 1 is a schematic view in elevation showing an embodiment of the invention;

#FIG. 2 is a sectional elevation of the embodiment of the invention shown in FIG. 1;

#FIG. 3 is a sectional elevation of another embodiment in accordance with the invention;

#In FIGS. 1 through 4 the embodiments illustrated to maintain this spaced relation by providing an inner liner with adequate hoop strength to resist radial expansion thereof. As will be described below, the embodiment of FIG. 5 accomplished the same objective by other means. Since the liquid stored in the inner chamber formed by the flexible liner of this invention is lighter than water, the resultant buoyant forces acting on this liquid will tend to cause it to flatten and spread radially toward the outer chamber. Means must be provided to restrict this to keep adequate spacing between the chambers.

#In FIG. 1 a system in accordance with the invention is illustrated schematically and consists of an outer chamber shown generally at 10 formed by liquid-impervious side walls 12 and bottom wall 14. A flexible, liquid-impervious membrane 16 is disposed in the chamber 10 in spaced relationship to the walls 12 and 14 and contains a liquid 18 of a specific density. The space between the membrane 16 and the outer chamber 10 contains another liquid 20 of greater density than the liquid 18. As described above, one embodiment of this invention is directed to the storage of petroleum in an environmentally safe manner by isolating the petroleum in a water jacket; however, it is contemplated that the invention may be applied to the similar storage of any liquids of different densities for any purpose such, for example, as wherein the temperature of the insulated liquid may be controlled by use of the isolating liquid as an insulating and/or heat applying or removing medium. It should be understood that, although specifically described as applied to the petroleum-water storage embodiment hereinafter described, the invention is applicable to systems involving any liquids of different densities.

#In a petroleum-water system, in accordance with the invention, the petroleum is less dense than water and therefore comprises the liquid 18 while water comprises the liquid 20. Because of the density differential, the membrane 16 containing the less dense petroleum 18 would normally assume a position extending above the surface of the surrounding water 20 as is indicated by the dotted line 18a. This would result in an area around the upper periphery of the membrane which would be unsupported by the water 20 and would, if not otherwise supported by mechanical means, expand toward the wall 2 until it ruptured or came in contact with the wall 12 thereby obviating the benefits of the invention.