Device for condensing volatile organic compounds from a storage or transport tank into oil

A device for condensing volatile organic compounds from a storage or transport tank into oil in the same or another storage or transport tank, the device comprising:

• a tank having a lower section for holding oil and an upper section for holding volatile organic compounds associated with the oil;
• a downcomer directing flow into the tank and having an upper part and having a lower end in communication with the lower section of the tank, the upper part being located at a predetermined height above the upper section of the tank and defining a flow path having a substantially constant cross sectional area perpendicular to the direction of flow;
• and
• a gas pipe connected to the flow path;
• wherein the predetermined height is sufficient to cause an inflow of gas from the upper section of the tank to the flow path when gravity causes oil to flow from the upper part of the downcomer to the second end of the downcomer.

A method for condensing volatile organic compounds from a storage or transport tank into oil in the same or another storage or transport tank, the method comprising the steps of:

• causing oil to flow into an upper part of a downcomer that is located at a predetermined height above the storage or transport tank, the downcomer defining a flow path having a substantially constant cross sectional area perpendicular to the direction of flow;
• allowing gravity to accelerate the oil down the flow path of the downcomer from the upper part to a lower end that is in communication with the storage or transport tank;
• and
• providing a gas pipe connecting gas in the storage or transport tank to the upper part of the downcomer;
• wherein the predetermined height is such that gravity creates a sufficient underpressure in the upper part of the downcomer to draw gas from the storage or transport tank into the upper part of the downcomer.