Patent ID: 6202707
Filing Date: 2001-03-20
Classification: F17C

Abstract:
A method for displacement a plurality of containers containing liquefied gas rich in methane and ullage gas, said liquefied gas having a temperature above -112.degree. C. (-170.degree. F.) and a pressure at essentially its bubble point, comprising the steps of:(a) feeding a pressurized displacement liquid to a first of said plurality of containers to discharge the pressurized liquefied gas and ullage gas therefrom, said displacement liquid having a pressure greater than the pressure of the liquefied gas;(b) pumping the displacement liquid from the first container to a second container of the plurality of containers to discharge liquefied gas therefrom and filling the void space in the first container created by removal of the displacement liquid with a vapor at a lower pressure than the pressure of displacement liquid in the second container; and(c) severing fluid communication between the first container from the second container and repeating steps (a) and (b) for all of said containers in succession until all of the containers are emptied of the liquefied gas and filled with the lower pressure vapor, except that for the last container the displacement liquid is pumped therefrom to an auxiliary container.