Method and apparatus for handling of covering gas
AssigneeABB Gas Technology AS
InventorsReidar Trefall, Kristian Utkilen
Life of this patent
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Abstract
A method for the handling of covering gas or inert gas in connection with a tank that conveys crude oil, during successive discharging and loading operations of the tank, is disclosed. The method is characterized by the fact that covering gas/inert gas is re-circulated in an approximate closed circulation by the following steps: that during discharging of the tank, covering gas is produced in a recognized manner known per se from the cargo to fill the gradually increasing void space in the tank, and that when the tank is filled again with crude oil, the gas from the tank is extracted again, and it is compressed and absorbed into the stabilized crude oil. An apparatus is mentioned for accomplishing the method.
Claims11
Apparatus for the handling of covering gas or inert gas in connection with a tank conveying crude oil, during successive discharging and loading operations of the tank, characterised by
- a circulation for re-circulating covering gas/inert gas, comprising:
- means of vaporization of a unit of cargo for the production of said covering gas, and means for filling a gradually increasing void space in the tank with covering gas, and
- an means for venting gas from the tank, as well as a means of compressing and absorption of the released tank gas.
A recycling circuit for the handling of a covering gas during successive discharging and loading operations of a tank conveying crude oil, said circuit comprising
- a line for selectively discharging crude oil from and delivering crude oil to a tank;
- a branch pipe extending from said line for venting a unit of the crude oil from said line during a discharge of crude oil from a tank and during delivery of crude oil to a tank;
- at least one heat exchanger in said branch pipe for heating the unit of crude oil passing therethrough;
- a column connected to said branch line for receiving the heated unit of crude oil therefrom and for separating vaporized gas from the heated unit of crude oil during a discharge of crude oil from a tank and for introducing gas into the unit of crude oil during delivery of crude oil to a tank;
- a first line extending from an upper end of said column for selectively delivering the separated gas in said column to the tank as a covering gas during a discharge of crude oil from a tank and for delivering covering gas from a tank to said column during delivery of crude oil to a tank;
- and
- a second line extending from a lower end of said column for returning crude oil in said column to the tank during a discharge of crude oil from a tank and during delivery of crude oil to a tank.
A method of handling a covering gas in a tank for conveying crude oil during a discharge operation and during a loading operation, said method comprising the steps of
- extracting a covering gas from a tank into a closed circuit during discharge of crude oil from a tank and recycling the extracted covering gas into the tank from said closed circuit during the discharge of crude oil from the tank to fill a gradually increasing void space in the tank;
- thereafter extracting the covering gas from the tank into said closed circuit during a subsequent delivery of crude oil into the tank;
- mixing the extracted covering gas with a portion of the crude oil being delivered to the tank in said closed circuit for absorption therein;
- and
- delivering the portion of crude oil with the covering gas therein to the tank.
Dependencies are inferred from the claim text.