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US 5,398,629 AGranted
Transportation of oil
AssigneeDen Norske Stats Oljeselskap A.S.
InventorReidar Wasenius
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AssigneeDen Norske Stats Oljeselskap A.S.
InventorReidar Wasenius
Estimating the term…
The invention relates to a method for loading and discharging tanks (1) for transporting oil, a method for transporting oil in tankers (1) and a pipe and valve system (6, 7, 8) in a tanker (1) for performing the method. According to the invention, gassing of hydrocarbon containing gas during loading and unloading is reduced by loading or unloading the cargo tanks (2) while the oil is maintained in contact with a generally saturated HC gas. This is done by saving the HC gas which is developed during loading or unloading, this gas later being used in further loading and unloading. This is made possible by a pipe and valve system (6, 7, 8) according to the invention. In accordance with one embodiment of the invention, the tanks are filled completely so that the oil is present in tank hatches (10) and risers (11) located at the top of the tanks (2). This results in that the gas volume above the cargo before a possible grounding is approximately equal to zero and, consequently, the necessary underpressure is obtained above the cargo for establishing a hydrostatic balance at the bottom of the tanker (1) with a minimum spill of a cargo.
A method of unloading a tanker (1) for transporting oil, said tanker (1) comprising cargo tanks (2) and slop/cargo (S/C) tanks (4), said task (2, 4) each comprising a tank hatch (10) with a riser pipe (11) and pressure/vacuum valves (12P, 12V) at the top of the task (2, 4), said tanker (1) further comprising a first pipe system (8) for inert gas communicating with the tanks (2, 4) through valves (13), and a second pipe system (9), wherein the oil prior to unloading is present in one or more of the tanks (2, 4) and during unloading leaves one or more tanks (2, 4) at a time at the bottom (24) thereof, characterized in that the unloading of a first tank is performed concurrently with an atmosphere generally constituted by saturated hydrocarbon containing gas being maintained in the tank, whereupon a second tank (2b) is unloaded concurrently with said saturated hydrocarbon containing gas being conveyed from said first tank (2a) in above the oil in said second tank.
A method for unloading a tanker (1) for transporting oil, said tanker (1) comprising cargo tanks (2) and slop/cargo (S/C) tanks (4), said tanks (2, 4) comprising a tank hatch (10) with a riser pipe (11) and pressure/vacuum valves (12P, 12V) at the top of the tanks (2, 4), said tanker (1) further comprising a first pipe system (8) for inert gas communicating with the tanks (2, 4) through valves (13), and a second pipe system (9), wherein the oil prior to unloading is present in one or more of the tanks (2, 4) and during unloading concurrently leaves a set consisting of one or more tanks (2, 4) at a time at the bottom (24) thereof, characterized in that the unloading of at least one set of tanks (2, 4) wholly or in part is performed concurrently with the surface of the oil in this set of tanks being kept in contact with an atmosphere generally constituted by saturated hydrocarbon containing gas, and further characterized in that during unloading of said set of tanks, a second gas is conveyed in above said saturated hydrocarbon containing gas, said second gas being lighter than the hydrocarbon containing gas.
A method of loading a tanker (1) for transporting oil, said tanker (1) comprising cargo tanks (2) and slop/cargo (S/C) tanks (4), the tanks (2, 4) each comprising a tank hatch (10) having a riser (11) and pressure/vacuum valves (12P, 12V) at the top of the tanks (2, 4), said tanker (1) further comprising a first pipe system (8) for inert gas communicating with the tanks (2, 4) through valves (13), and a second pipe system (9), the oil during loading being conveyed into said cargo tanks (2) at the bottom (24) thereof, characterized in that loading of a first tank (2b) is performed concurrently with the surface of the oil in said tank being kept in contact with an atmosphere constituted generally by saturated hydrocarbon containing gas, the saturated hydrocarbon containing gas displaced from the tank being transferred to the bottom of a second tank (2a) subsequently to be loaded.
A pipe and valve system for a tanker (1) for transporting oil, said tanker (1) comprising cargo tanks (2) and slop/cargo (S/C) tanks (4), said tanks (2, 4) each comprising a tank bottom (24), a tank deck (25) and a tank hatch (10) with a riser (11) and pressure/vacuum valves (12P, 12V) at the top of the tanks (2, 3, 4), said tanker (1) further comprising a first pipe system (8) for inert gas communicating with the tanks (2, 4) through valves (13), and a second pipe system, characterized in that additionally a header (6) is arranged which through pipes (7) communicates with the tanks (2, 4), valves (14) being arranged in the pipes (7), in that the risers (11) with valves (12P, 12V) extend into the header (6), and in that, in addition, valves (15) are arranged for regulating a connection between the header (6) and the pipe system (8) for inert gas.
Dependencies are inferred from the claim text.