GB1027678A - Improvements in or relating to transport and storage of liquefied gases - Google Patents

Abstract

1,027,678. Storing liquefied gases. SHELL RESEARCH Ltd. March 5, 1963, No. 8714/63. Heading F4P. [Also in Divisions B1 and F1] A method of storing liquefied gas at atmospheric pressure comprises floating the liquefied gas on a second inert liquid in which the liquefied gas is at least partially soluble and which has at a temperature not exceeding 60‹ C. a vapour pressure not exceeding one atmosphere and a density greater than that of the liquefied gas, and condensing liquefied gas which has vaporized due to heat transferred from the second liquid and returning the condensate to the body of liquefied gas. Over a period the temperature of the second liquid is reduced with consequential dissolution of the liquefied gas in the second liquid until a temperature may be reached at which the liquefied gas is fully dissolved in the second liquid. Examples of liquefied gases which may be stored are acetylene, ethylene, ethane, propane, propene, nbutane, iso-butane, n-butene, iso-butene and mixtures thereof, and examples of the second liquid are crude-petroleum, topped crude, residual fuel oil, lubricating oil distillates, catalytically cracked cycle oil, thermally cracked gas oil, straight run gas oils, kerosines, heavy gasoline fractions and mixtures thereof. Fig. 4 shows liquefied gas 10 floating on a carrier liquid within a tank 1 flanked by wing tanks 2, 3 of a ship, the liquefied gas being confined within a rectangular skirt retainer 11. The retainer 11 may be supported from the roof, sides or bottom of the tank 1; it may have perforations therein and may be provided with a perforated bottom plate. A floating suction member 25 communicates by means of a conduit 26 with a cyclone 27 having a part 28 communicating with a vacuum source (not shown) and a port 29 communicating with a pump 30, whereby the liquefied gas may be discharged from the ship; gas formed during discharge of the liquefied gas may be condensed. Alternatively, the liquefied gas may be discharged by an electrically-operated submerged pump 35 having a floating suction 36. A condenser 6 is provided for condensing the liquefied gas which has been vaporized during storage, the condenser having a vent 5 for entry of gas to the condenser and for return of the condensate to the tank 1. The latter is loaded with liquefied gas by means of a swing- arm which is slowly raised to ensure delivery of the liquefied gas to the surface of the carrier liquid with minimum kinetic energy. In a second embodiment, Fig. 3, the skirt retainer 11 is replaced by a floating pan retainer 17 which is restrained to move in a vertical direction by runners 20 directed by guides 18 extending from the roof to the floor of the tank 1. Dissolution of the liquefied gas in the carrier liquid takes place by vapour contact. The retainer 11 or 17 may be dispensed with.