Apparatus and method for gravitational separation of the phases of a two phase liquid

An apparatus for the gravitational separation of the first and second liquid phases of a two phase liquid containing predominantly a continuous first liquid phase with a dispersed second liquid phase, the second liquid having a lower specific gravity than the first liquid, the apparatus comprising:

• an upright tank defining an interior chamber with an upper portion and a lower portion;
• a feed inlet by which the two phase liquid is introduced into the lower portion of the chamber;
• a first liquid outlet in the lower portion of the chamber by which separated first liquid is removed from the tank;
• a second liquid outlet in the upper portion of the chamber by which separated second liquid is removed from the tank;
• the upper portion of the chamber having an upward flow zone through which the two phase liquid from the feed inlet rises, with the dispersed second liquid rising more than the first liquid and being separated therefrom due to the second liquid's lower specific gravity, the second liquid forming a floating layer above the remaining liquid with an interface therebetween that is lower than the second liquid outlet;
• a conduit that can direct separated second liquid from the floating layer to the second liquid outlet, the conduit comprising a barrier that permits separated second liquid to flow into the conduit only when the top of the floating layer reaches a predetermined height, and a sloped bottom to direct the second liquid to the second liquid outlet;
• the upper portion of the chamber also having an array of baffles contiguous to the upward flow zone, the baffles defining channels through which separated first liquid descends, the channels being directed downwardly away from the upward flow zone;
• passages isolated from the chamber that communicate with the channels and carry separated first liquid to the first liquid outlet;
• a valve for controlling the flow of separated first liquid from the first liquid outlet;
• a sensor system for determining the height of the interface between the floating layer and the remaining liquid;
• and
• the valve being responsive to the sensor system to regulate the flow of separated first liquid from the first liquid outlet such that the height of the floating layer can be held generally constant.