Method and arrangement at a loading column

#The present application is the U.S. national stage application of International Application PCT/NO02/00463, filed Dec. 5, 2002, which international application was published on Jun. 12, 2003 as International Publication WO 03/048028. The International Application claims priority of Norwegian Patent Application 20015963, filed Dec. 6, 2001.

#This invention regards a method of reducing that proportion of volatile organic compounds (VOC) which is separated from oil, in particular crude oil, during the filling of tanks, such as during the loading of a ship from a terminal, a production platform or a floating loading device. The invention also comprises an arrangement for carrying out the method. The arrangement may also be used for reducing evaporation of gas during the filling of single components such as propane, butane, ethane and liquefied natural gas.

#Crude oil is made up of different components stabilised at a specified pressure and a specified temperature. If these conditions are altered, either through a reduction in pressure or an increase in temperature, a proportion of the volatile components will separate out and gasify. These components consist of volatile organic compounds such as e.g. methane, propane, butane and ethane, and are termed VOC. Systems currently exist for removal of these gases. As opposed to the arrangement of the present application, today's systems are based on treating the already separated gases by providing a process arrangement for treatment of the exhaust gas subsequent to evaporation. The plants are complex and will require a lot of energy, as pressure and temperature are employed to bring the gases back to a liquid state.

#The following describes a non-limiting example of a preferred arrangement and method illustrated in the accompanying drawing, in which:

#FIG. 1 schematically shows a section of a loading arrangement in which oil is pumped on board a tanker equipped with a loading column. A spiral provided with arrows indicates the flow path of the oil in the loading column, while ellipses, also provided with arrows, indicate a possible flow path for gas in the loading column.

#In the drawing, reference number 1 denotes a ship with a transport tank 2 for oil. When empty, the ship 1 rides relatively high in the water 4. Oil flows from a pumping station (not shown) through a loading pipe 6, tangentially into the upper end portion 10 of a loading column 8. The cross section of the loading column 8 is significantly larger than that of the loading pipe 6. The loading pipe 6 may be in the form of e.g. a pipe, a hose or another suitable hollow body.

#In this preferred embodiment, the loading column 8 constitutes a part of the transport tank 2 on board the ship 1 and has been formed as a cylindrical silo, the upper end portion 10 of which is equipped with a cover 12, and the lower end portion 14 if which is equipped with an outlet 16 that discharges into the transport tank 2.

#The upper portion 10 of the loading column 8 is connected to and in communication with the transport tank 2 via branch pipes 18 and 20, as well as valves 22 and 24. The pressure relief valve 22 is designed to open for flow from the loading column 8 to the cargo hold 2 at a predetermined pressure differential, while the pressure relief valve 24 is designed to open for flow from the cargo hold 2 to the loading column 8 at a predetermined pressure differential.