Three stage centrifuge and method for separating water and solids from petroleum products

A three stage centrifuge for separating oil, water and solids from a petroleum product emulsion comprising:

• a rotatable bowl for receiving and rotating the emulsion in order to exert centrifugal force on the emulsion to separate the emulsion into water and oil pools and to move the solids radially outward, with the rotatable bowl having a tapered beach section at one end with a solids discharge port;
• drive means for rotating the rotatable bowl;
• a generally cylindrical shaped conveyor auger rotatably mounted within the rotatable bowl and having an emulsion inlet and helically wound flights for contacting solids and for moving the solids through a water pool formed in the rotatable bowl to the discharge port;
• hydraulic drive means for rotating the conveyor auger;
• pressure sensing and control means for sensing and varying pressure to the hydraulic drive means with varying torque on the conveyor auger exerted by solids in the emulsion in order to control a speed of the conveyor auger;
• a feed pump for pumping emulsion to the emulsion inlet and into the rotatable bowl with a minimum of turbulence and substantially without breaking solid particles in the emulsion;
• a first baffle plate mounted to the conveyor auger adjacent to the emulsion inlet and a second baffle plate mounted to the conveyor auger adjacent to a fluid's discharge end of the rotatable bowl;
• a first oil discharge tube mounted to the rotatable bowl between the first and second baffle plates and a second oil discharge tube mounted to the rotatable bowl between the first and second baffle plates with the first and second oil discharge tubes axially offset and adjustable to contact an oil pool formed within the rotatable bowl for discharging the oil;
• an adjustable water weir mounted to an end of the rotatable bowl for contacting a water pool formed within the rotatable bowl and for discharging the water from the rotatable bowl;
• and
• a third baffle plate associated with the emulsion inlet for preventing disruption of the oil and water pools by incoming emulsion.

A method of processing a petroleum fluid to remove water, and solids comprising:

• agitating the fluid to provide a homogeneous mixture;
• heating the fluid to a selected temperature;
• pumping the fluid with a minimum of turbulence and substantially without breaking of solid particles in the fluid at a selected feed rate to a generally cylindrical rotatable bowl having a beach section of reduced cross section;
• rotating the fluid within the rotatable bowl in order to separate the fluid into separate oil and water pools and to throw solids in the fluid outward by centrifugal force within the rotatable bowl;
• conveying the solids within the rotatable bowl through a water pool formed in the beach area of the rotatable bowl to a solids discharge port;
• dischargin oil from the rotatable bowl through an oil discharge means having an oil discharge tube within the rotatable bowl placed into the oil pool and located between oil baffle plates within the rotatable bowl;
• discharging water from the rotatable bowl through a water discharge means placed into the water pool;
• sensing and controlling a rate of conveying of the solids to the solids discharge port in response to the amount of solids;
• and
• baffling incoming fluid into the rotatable bowl to prevent disruption of the oil and water pools.